From 327020750ff5e5a7a3b9f07b3dd65661b33ce9b7 Mon Sep 17 00:00:00 2001
From: Brendan Forster <github@brendanforster.com>
Date: Wed, 18 Mar 2020 08:52:50 -0300
Subject: [PATCH] add convention test for preview APIs (#2154)

---
 .../Clients/ObservableIssuesLabelsClient.cs   |  14 +--
 .../ObservableRepoCollaboratorsClient.cs      |  10 +-
 .../Clients/ObservableRepositoriesClient.cs   |  16 +--
 .../ObservableRepositoryInvitationsClient.cs  |  26 ++--
 .../Clients/ObservableTeamsClient.cs          |  18 +--
 Octokit.Tests.Conventions/PreviewsTests.cs    |  99 +++++++++++++++
 Octokit.Tests/Clients/CommitsClientTests.cs   |   3 +-
 Octokit.Tests/Clients/IssuesClientTests.cs    |   8 +-
 .../Clients/IssuesLabelsClientTests.cs        |  48 +++----
 .../Clients/MiscellaneousClientTests.cs       |   4 +-
 .../Clients/PullRequestsClientTests.cs        |   8 +-
 .../Clients/RepoCollaboratorsClientTests.cs   |  14 +--
 .../Clients/RepositoriesClientTests.cs        |  78 ++++--------
 .../Clients/RepositoryBranchesClientTests.cs  | 118 +++++++++---------
 .../RepositoryInvitationsClientTests.cs       |  13 +-
 .../Clients/RepositoryPagesClientTests.cs     |   4 +-
 .../Clients/RepositoryTrafficClientTests.cs   |  16 +--
 Octokit.Tests/Clients/SearchClientTests.cs    |  22 ++--
 Octokit.Tests/Clients/TagsClientTests.cs      |   4 +-
 Octokit.Tests/Clients/TeamsClientTests.cs     |  42 ++-----
 .../Clients/UserGpgKeysClientTests.cs         |  19 +--
 Octokit.Tests/Http/ConnectionTests.cs         |   4 +-
 Octokit.Tests/Http/JsonHttpPipelineTests.cs   |   2 +-
 .../ObservableIssuesLabelsClientTests.cs      |  28 ++---
 .../ObservableRepoCollaboratorsClientTests.cs |  30 ++---
 .../ObservableRepositoriesClientTests.cs      |  12 +-
 .../Reactive/ObservableTeamsClientTests.cs    |  12 +-
 Octokit/Clients/CommitsClient.cs              |   2 +-
 Octokit/Clients/IssuesClient.cs               |   8 +-
 Octokit/Clients/IssuesLabelsClient.cs         |  36 +++---
 Octokit/Clients/MiscellaneousClient.cs        |   4 +-
 Octokit/Clients/PullRequestsClient.cs         |   4 +-
 Octokit/Clients/RepoCollaboratorsClient.cs    |  12 +-
 Octokit/Clients/RepositoriesClient.cs         |  30 ++---
 Octokit/Clients/RepositoryBranchesClient.cs   | 114 +++++++++--------
 .../Clients/RepositoryInvitationsClient.cs    |  22 ++--
 Octokit/Clients/RepositoryPagesClient.cs      |   4 +-
 Octokit/Clients/RepositoryTrafficClient.cs    |  16 +--
 Octokit/Clients/SearchClient.cs               |   2 +-
 Octokit/Clients/TagsClient.cs                 |   4 +-
 Octokit/Clients/TeamsClient.cs                |  30 ++---
 Octokit/Clients/UserGpgKeysClient.cs          |   8 +-
 Octokit/Helpers/AcceptHeaders.cs              |  36 +-----
 Octokit/Http/JsonHttpPipeline.cs              |   2 +-
 44 files changed, 497 insertions(+), 509 deletions(-)
 create mode 100644 Octokit.Tests.Conventions/PreviewsTests.cs

diff --git a/Octokit.Reactive/Clients/ObservableIssuesLabelsClient.cs b/Octokit.Reactive/Clients/ObservableIssuesLabelsClient.cs
index f3400c14..8781d1f0 100644
--- a/Octokit.Reactive/Clients/ObservableIssuesLabelsClient.cs
+++ b/Octokit.Reactive/Clients/ObservableIssuesLabelsClient.cs
@@ -71,7 +71,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.IssueLabels(owner, name, number), null, AcceptHeaders.LabelsApiPreview, options);
+            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.IssueLabels(owner, name, number), options);
         }
 
         /// <summary>
@@ -87,7 +87,7 @@ namespace Octokit.Reactive
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.IssueLabels(repositoryId, number), null, AcceptHeaders.LabelsApiPreview, options);
+            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.IssueLabels(repositoryId, number), options);
         }
 
         /// <summary>
@@ -133,7 +133,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.Labels(owner, name), null, AcceptHeaders.LabelsApiPreview, options);
+            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.Labels(owner, name), options);
         }
 
         /// <summary>
@@ -148,7 +148,7 @@ namespace Octokit.Reactive
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.Labels(repositoryId), null, AcceptHeaders.LabelsApiPreview, options);
+            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.Labels(repositoryId), options);
         }
 
         /// <summary>
@@ -197,7 +197,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.MilestoneLabels(owner, name, number), null, AcceptHeaders.LabelsApiPreview, options);
+            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.MilestoneLabels(owner, name, number), options);
         }
 
         /// <summary>
@@ -213,7 +213,7 @@ namespace Octokit.Reactive
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.MilestoneLabels(repositoryId, number), null, AcceptHeaders.LabelsApiPreview, options);
+            return _connection.GetAndFlattenAllPages<Label>(ApiUrls.MilestoneLabels(repositoryId, number), options);
         }
 
         /// <summary>
@@ -499,4 +499,4 @@ namespace Octokit.Reactive
             return _client.RemoveAllFromIssue(repositoryId, number).ToObservable();
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Octokit.Reactive/Clients/ObservableRepoCollaboratorsClient.cs b/Octokit.Reactive/Clients/ObservableRepoCollaboratorsClient.cs
index e19666a4..6bee5da3 100644
--- a/Octokit.Reactive/Clients/ObservableRepoCollaboratorsClient.cs
+++ b/Octokit.Reactive/Clients/ObservableRepoCollaboratorsClient.cs
@@ -146,7 +146,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNull(request, nameof(request));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<User>(ApiUrls.RepoCollaborators(owner, name), request.ToParametersDictionary(), AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<User>(ApiUrls.RepoCollaborators(owner, name), request.ToParametersDictionary(), options);
         }
 
         /// <summary>
@@ -164,7 +164,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNull(request, nameof(request));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<User>(ApiUrls.RepoCollaborators(repositoryId), request.ToParametersDictionary(), AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<User>(ApiUrls.RepoCollaborators(repositoryId), request.ToParametersDictionary(), options);
         }
 
         /// <summary>
@@ -319,7 +319,7 @@ namespace Octokit.Reactive
         /// </remarks>
         /// <param name="owner">The owner of the repository</param>
         /// <param name="name">The name of the repository</param>
-        /// <param name="user">The username of the prospective collaborator</param>        
+        /// <param name="user">The username of the prospective collaborator</param>
         public IObservable<RepositoryInvitation> Invite(string owner, string name, string user)
         {
             Ensure.ArgumentNotNullOrEmptyString(owner, nameof(owner));
@@ -372,7 +372,7 @@ namespace Octokit.Reactive
         /// See the <a href="http://developer.github.com/v3/repos/collaborators/#list">API documentation</a> for more information.
         /// </remarks>
         /// <param name="repositoryId">The id of the repository</param>
-        /// <param name="user">The username of the prospective collaborator</param>   
+        /// <param name="user">The username of the prospective collaborator</param>
         /// <param name="permission">The permission to set. Only valid on organization-owned repositories.</param>
         public IObservable<RepositoryInvitation> Invite(long repositoryId, string user, CollaboratorRequest permission)
         {
@@ -417,4 +417,4 @@ namespace Octokit.Reactive
             return _client.Delete(repositoryId, user).ToObservable();
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Octokit.Reactive/Clients/ObservableRepositoriesClient.cs b/Octokit.Reactive/Clients/ObservableRepositoriesClient.cs
index 1f399145..ddeb1338 100644
--- a/Octokit.Reactive/Clients/ObservableRepositoriesClient.cs
+++ b/Octokit.Reactive/Clients/ObservableRepositoriesClient.cs
@@ -164,7 +164,7 @@ namespace Octokit.Reactive
         /// <returns>A <see cref="IReadOnlyPagedCollection{Repository}"/> of <see cref="Repository"/>.</returns>
         public IObservable<Repository> GetAllPublic()
         {
-            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.AllPublicRepositories(), null, AcceptHeaders.LicensesApiPreview);
+            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.AllPublicRepositories());
         }
 
         /// <summary>
@@ -181,7 +181,7 @@ namespace Octokit.Reactive
 
             var url = ApiUrls.AllPublicRepositories(request.Since);
 
-            return _connection.GetAndFlattenAllPages<Repository>(url, null, AcceptHeaders.LicensesApiPreview);
+            return _connection.GetAndFlattenAllPages<Repository>(url);
         }
 
         /// <summary>
@@ -207,7 +207,7 @@ namespace Octokit.Reactive
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.Repositories(), null, AcceptHeaders.LicensesApiPreview, options);
+            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.Repositories(), options);
         }
 
         /// <summary>
@@ -238,7 +238,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNull(request, nameof(request));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.Repositories(), request.ToParametersDictionary(), AcceptHeaders.LicensesApiPreview);
+            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.Repositories(), request.ToParametersDictionary());
         }
 
         /// <summary>
@@ -264,7 +264,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNullOrEmptyString(login, nameof(login));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.Repositories(login), null, AcceptHeaders.LicensesApiPreview, options);
+            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.Repositories(login), null, options);
         }
 
         /// <summary>
@@ -292,7 +292,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNullOrEmptyString(organization, nameof(organization));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.OrganizationRepositories(organization), null, AcceptHeaders.LicensesApiPreview, options);
+            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.OrganizationRepositories(organization), options);
         }
 
         /// <summary>
@@ -586,7 +586,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.RepositoryTeams(owner, name), null, AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.RepositoryTeams(owner, name), options);
         }
 
         /// <summary>
@@ -602,7 +602,7 @@ namespace Octokit.Reactive
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.RepositoryTeams(repositoryId), null, AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.RepositoryTeams(repositoryId), options);
         }
 
         /// <summary>
diff --git a/Octokit.Reactive/Clients/ObservableRepositoryInvitationsClient.cs b/Octokit.Reactive/Clients/ObservableRepositoryInvitationsClient.cs
index 381ec24e..06c8a8d7 100644
--- a/Octokit.Reactive/Clients/ObservableRepositoryInvitationsClient.cs
+++ b/Octokit.Reactive/Clients/ObservableRepositoryInvitationsClient.cs
@@ -24,8 +24,8 @@ namespace Octokit.Reactive
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#accept-a-repository-invitation">API documentation</a> for more information.
-        /// </remarks>        
-        /// <param name="invitationId">The id of the invitation.</param>   
+        /// </remarks>
+        /// <param name="invitationId">The id of the invitation.</param>
         public IObservable<bool> Accept(int invitationId)
         {
             return _client.Accept(invitationId).ToObservable();
@@ -36,8 +36,8 @@ namespace Octokit.Reactive
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#decline-a-repository-invitation">API documentation</a> for more information.
-        /// </remarks>        
-        /// <param name="invitationId">The id of the invitation.</param>   
+        /// </remarks>
+        /// <param name="invitationId">The id of the invitation.</param>
         public IObservable<bool> Decline(int invitationId)
         {
             return _client.Decline(invitationId).ToObservable();
@@ -50,7 +50,7 @@ namespace Octokit.Reactive
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#delete-a-repository-invitation">API documentation</a> for more information.
         /// </remarks>
         /// <param name="repositoryId">The id of the repository.</param>
-        /// <param name="invitationId">The id of the invitation.</param>        
+        /// <param name="invitationId">The id of the invitation.</param>
         public IObservable<bool> Delete(long repositoryId, int invitationId)
         {
             return _client.Delete(repositoryId, invitationId).ToObservable();
@@ -63,7 +63,7 @@ namespace Octokit.Reactive
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#update-a-repository-invitation">API documentation</a> for more information.
         /// </remarks>
         /// <param name="repositoryId">The id of the repository.</param>
-        /// <param name="invitationId">The id of the invitatio.n</param>   
+        /// <param name="invitationId">The id of the invitatio.n</param>
         /// <param name="permissions">The permission to set.</param>
         public IObservable<RepositoryInvitation> Edit(long repositoryId, int invitationId, InvitationUpdate permissions)
         {
@@ -77,7 +77,7 @@ namespace Octokit.Reactive
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#list-a-users-repository-invitations">API documentation</a> for more information.
-        /// </remarks>        
+        /// </remarks>
         public IObservable<RepositoryInvitation> GetAllForCurrent()
         {
             return GetAllForCurrent(ApiOptions.None);
@@ -89,11 +89,11 @@ namespace Octokit.Reactive
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#list-a-users-repository-invitations">API documentation</a> for more information.
         /// </remarks>
-        /// <param name="options">Options for changing the API response</param>        
+        /// <param name="options">Options for changing the API response</param>
         public IObservable<RepositoryInvitation> GetAllForCurrent(ApiOptions options)
         {
             Ensure.ArgumentNotNull(options, nameof(options));
-            return _connection.GetAndFlattenAllPages<RepositoryInvitation>(ApiUrls.UserInvitations(), null, AcceptHeaders.InvitationsApiPreview, options);
+            return _connection.GetAndFlattenAllPages<RepositoryInvitation>(ApiUrls.UserInvitations(), null, null, options);
         }
 
         /// <summary>
@@ -101,8 +101,8 @@ namespace Octokit.Reactive
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#list-invitations-for-a-repository">API documentation</a> for more information.
-        /// </remarks>        
-        /// <param name="repositoryId">The id of the repository</param>  
+        /// </remarks>
+        /// <param name="repositoryId">The id of the repository</param>
         public IObservable<RepositoryInvitation> GetAllForRepository(long repositoryId)
         {
             return GetAllForRepository(repositoryId, ApiOptions.None);
@@ -113,13 +113,13 @@ namespace Octokit.Reactive
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#list-invitations-for-a-repository">API documentation</a> for more information.
-        /// </remarks>        
+        /// </remarks>
         /// <param name="repositoryId">The id of the repository</param>
         /// <param name="options">Options for changing the API response</param>
         public IObservable<RepositoryInvitation> GetAllForRepository(long repositoryId, ApiOptions options)
         {
             Ensure.ArgumentNotNull(options, nameof(options));
-            return _connection.GetAndFlattenAllPages<RepositoryInvitation>(ApiUrls.RepositoryInvitations(repositoryId), null, AcceptHeaders.InvitationsApiPreview, options);
+            return _connection.GetAndFlattenAllPages<RepositoryInvitation>(ApiUrls.RepositoryInvitations(repositoryId), null, null, options);
         }
     }
 }
diff --git a/Octokit.Reactive/Clients/ObservableTeamsClient.cs b/Octokit.Reactive/Clients/ObservableTeamsClient.cs
index 603aae6c..4630bbdc 100644
--- a/Octokit.Reactive/Clients/ObservableTeamsClient.cs
+++ b/Octokit.Reactive/Clients/ObservableTeamsClient.cs
@@ -64,7 +64,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNullOrEmptyString(org, nameof(org));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.OrganizationTeams(org), null, AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.OrganizationTeams(org), options);
         }
 
         /// <summary>
@@ -87,7 +87,7 @@ namespace Octokit.Reactive
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.UserTeams(), null, AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.UserTeams(), options);
         }
 
         /// <summary>
@@ -114,11 +114,11 @@ namespace Octokit.Reactive
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.TeamChildTeams(id), null, AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<Team>(ApiUrls.TeamChildTeams(id), options);
         }
 
         /// <summary>
-        /// Returns all members of the given team. 
+        /// Returns all members of the given team.
         /// </summary>
         /// <param name="id">The team identifier</param>
         /// <remarks>
@@ -132,7 +132,7 @@ namespace Octokit.Reactive
         }
 
         /// <summary>
-        /// Returns all members of the given team. 
+        /// Returns all members of the given team.
         /// </summary>
         /// <remarks>
         /// https://developer.github.com/v3/orgs/teams/#list-team-members
@@ -145,7 +145,7 @@ namespace Octokit.Reactive
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<User>(ApiUrls.TeamMembers(id), null, AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<User>(ApiUrls.TeamMembers(id), options);
         }
 
         /// <summary>
@@ -177,7 +177,7 @@ namespace Octokit.Reactive
             Ensure.ArgumentNotNull(request, nameof(request));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<User>(ApiUrls.TeamMembers(id), request.ToParametersDictionary(), AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<User>(ApiUrls.TeamMembers(id), request.ToParametersDictionary(), options);
         }
 
         /// <summary>
@@ -249,7 +249,7 @@ namespace Octokit.Reactive
         }
 
         /// <summary>
-        /// Gets whether the user with the given <paramref name="login"/> 
+        /// Gets whether the user with the given <paramref name="login"/>
         /// is a member of the team with the given <paramref name="id"/>.
         /// A <see cref="NotFoundException"/> is thrown if the user is not a member.
         /// </summary>
@@ -286,7 +286,7 @@ namespace Octokit.Reactive
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.TeamRepositories(id), null, AcceptHeaders.NestedTeamsPreview, options);
+            return _connection.GetAndFlattenAllPages<Repository>(ApiUrls.TeamRepositories(id), options);
         }
 
         /// <summary>
diff --git a/Octokit.Tests.Conventions/PreviewsTests.cs b/Octokit.Tests.Conventions/PreviewsTests.cs
new file mode 100644
index 00000000..8fd06610
--- /dev/null
+++ b/Octokit.Tests.Conventions/PreviewsTests.cs
@@ -0,0 +1,99 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using Xunit;
+
+namespace Octokit.Tests.Conventions
+{
+    public class PreviewsTests
+    {
+        [Fact]
+        public void NoStalePreviews()
+        {
+            var fields = typeof(AcceptHeaders).GetFields(BindingFlags.Public | BindingFlags.Static);
+
+            var values = fields.Where(f => f.GetCustomAttribute<ObsoleteAttribute>() == null)
+                               .ToDictionary(f => f.Name, f => f.GetValue(null).ToString());
+
+            var previewKeys = new string[]
+            {
+                "wyandotte",
+                "ant-man",
+                "squirrel-girl",
+                "mockingbird",
+                "machine-man",
+                "inertia",
+                "cloak",
+                "black-panther",
+                "giant-sentry-fist",
+                "mercy",
+                "scarlet-witch",
+                "sailor-v",
+                "zzzax",
+                "luke-cage",
+                "antiope",
+                "starfox",
+                "fury",
+                "flash",
+                "surtur",
+                "corsair",
+                "sombra",
+                "shadow-cat",
+                "switcheroo",
+                "groot",
+                "gambit",
+                "dorian",
+                "lydian",
+                "london",
+                "baptiste",
+                "doctor-strange",
+                "nebula",
+                // Enterprise-specific previews
+                // https://developer.github.com/enterprise/2.20/v3/enterprise-admin/pre_receive_environments/
+                "eye-scream",
+                // this is a new preview that seems undocumented but get mentioned here
+                // https://developer.github.com/changes/2/#--multi-line-comments
+                "comfort-fade"
+            };
+
+            var previewAcceptHeaders = previewKeys.Select(k => $"application/vnd.github.{k}-preview+json");
+
+            var defaultHeaders = new string[]
+            {
+                // default content types
+                "application/vnd.github.v3",
+                "application/vnd.github.v3+json",
+                // for places where content or markdown can be rendered
+                "application/vnd.github.v3.html",
+                "application/vnd.github.v3.raw",
+                // https://developer.github.com/v3/repos/commits/#get-a-single-commit
+                "application/vnd.github.v3.sha",
+                // https://developer.github.com/v3/activity/starring/#alternative-response-with-star-creation-timestamps
+                "application/vnd.github.v3.star+json"
+            };
+
+            var validHeaders = defaultHeaders.Concat(previewAcceptHeaders);
+
+            var notAllowedHeaders = values.Values.ToList().Except(validHeaders).OrderBy(k => k);
+            if (notAllowedHeaders.Any())
+            {
+                throw new InvalidAcceptHeadersFound(notAllowedHeaders);
+            }
+        }
+    }
+
+    public class InvalidAcceptHeadersFound : Exception
+    {
+        public InvalidAcceptHeadersFound(IEnumerable<string> notAllowedHeaders)
+            : base(CreateMessage(notAllowedHeaders))
+        { }
+
+        static string CreateMessage(IEnumerable<string> notAllowedHeaders)
+        {
+            return string.Format("Accept headers in use but not allowed: {0}{1}",
+               Environment.NewLine,
+               string.Join(Environment.NewLine, notAllowedHeaders));
+        }
+    }
+}
diff --git a/Octokit.Tests/Clients/CommitsClientTests.cs b/Octokit.Tests/Clients/CommitsClientTests.cs
index b24478ea..6f04edc0 100644
--- a/Octokit.Tests/Clients/CommitsClientTests.cs
+++ b/Octokit.Tests/Clients/CommitsClientTests.cs
@@ -18,8 +18,7 @@ public class CommitsClientTests
 
             await client.Get("owner", "repo", "reference");
 
-            connection.Received().Get<Commit>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/git/commits/reference"), null,
-                "application/vnd.github.cryptographer-preview+sha");
+            connection.Received().Get<Commit>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/git/commits/reference"));
         }
 
         [Fact]
diff --git a/Octokit.Tests/Clients/IssuesClientTests.cs b/Octokit.Tests/Clients/IssuesClientTests.cs
index 71659e82..893c3561 100644
--- a/Octokit.Tests/Clients/IssuesClientTests.cs
+++ b/Octokit.Tests/Clients/IssuesClientTests.cs
@@ -493,7 +493,7 @@ namespace Octokit.Tests.Clients
 
                 client.Lock("fake", "repo", 42);
 
-                connection.Received().Put<Issue>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/lock"), Arg.Any<object>(), Arg.Any<string>(), Arg.Is<string>(u => u.ToString() == "application/vnd.github.the-key-preview+json"));
+                connection.Received().Put<Issue>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/lock"), Arg.Any<object>());
             }
 
             [Fact]
@@ -504,7 +504,7 @@ namespace Octokit.Tests.Clients
 
                 client.Lock(1, 42);
 
-                connection.Received().Put<Issue>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/lock"), Arg.Any<object>(), Arg.Any<string>(), Arg.Is<string>(u => u.ToString() == "application/vnd.github.the-key-preview+json"));
+                connection.Received().Put<Issue>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/lock"), Arg.Any<object>());
             }
 
             [Fact]
@@ -531,7 +531,7 @@ namespace Octokit.Tests.Clients
 
                 client.Unlock("fake", "repo", 42);
 
-                connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/lock"), Arg.Any<object>(), Arg.Is<string>(u => u.ToString() == "application/vnd.github.the-key-preview+json"));
+                connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/lock"));
             }
 
             [Fact]
@@ -542,7 +542,7 @@ namespace Octokit.Tests.Clients
 
                 client.Unlock(1, 42);
 
-                connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/lock"), Arg.Any<object>(), Arg.Is<string>(u => u.ToString() == "application/vnd.github.the-key-preview+json"));
+                connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/lock"));
             }
 
             [Fact]
diff --git a/Octokit.Tests/Clients/IssuesLabelsClientTests.cs b/Octokit.Tests/Clients/IssuesLabelsClientTests.cs
index dfe82b79..4e5f0e8f 100644
--- a/Octokit.Tests/Clients/IssuesLabelsClientTests.cs
+++ b/Octokit.Tests/Clients/IssuesLabelsClientTests.cs
@@ -28,7 +28,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForIssue("fake", "repo", 42);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), null, "application/vnd.github.symmetra-preview+json", Args.ApiOptions);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), Args.ApiOptions);
             }
 
             [Fact]
@@ -39,7 +39,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForIssue(1, 42);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), null, "application/vnd.github.symmetra-preview+json", Args.ApiOptions);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Args.ApiOptions);
             }
 
             [Fact]
@@ -57,7 +57,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForIssue("fake", "repo", 42, options);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), null, "application/vnd.github.symmetra-preview+json", options);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), options);
             }
 
             [Fact]
@@ -75,7 +75,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForIssue(1, 42, options);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), null, "application/vnd.github.symmetra-preview+json", options);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), options);
             }
 
             [Fact]
@@ -108,7 +108,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForRepository("fake", "repo");
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), null, "application/vnd.github.symmetra-preview+json", Args.ApiOptions);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), Args.ApiOptions);
             }
 
             [Fact]
@@ -119,7 +119,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForRepository(1);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), null, "application/vnd.github.symmetra-preview+json", Args.ApiOptions);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), Args.ApiOptions);
             }
 
             [Fact]
@@ -137,7 +137,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForRepository("fake", "repo", options);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), null, "application/vnd.github.symmetra-preview+json", options);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), options);
             }
 
             [Fact]
@@ -155,7 +155,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForRepository(1, options);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), null, "application/vnd.github.symmetra-preview+json", options);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), options);
             }
 
             [Fact]
@@ -188,7 +188,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForMilestone("fake", "repo", 42);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/milestones/42/labels"), null, "application/vnd.github.symmetra-preview+json", Args.ApiOptions);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/milestones/42/labels"), Args.ApiOptions);
             }
 
             [Fact]
@@ -199,7 +199,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForMilestone(1, 42);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/milestones/42/labels"), null, "application/vnd.github.symmetra-preview+json", Args.ApiOptions);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/milestones/42/labels"), Args.ApiOptions);
             }
 
             [Fact]
@@ -217,7 +217,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForMilestone("fake", "repo", 42, options);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/milestones/42/labels"), null, "application/vnd.github.symmetra-preview+json", options);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/milestones/42/labels"), options);
             }
 
             [Fact]
@@ -235,7 +235,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllForMilestone(1, 42, options);
 
-                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/milestones/42/labels"), null, "application/vnd.github.symmetra-preview+json", options);
+                connection.Received().GetAll<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/milestones/42/labels"), options);
             }
 
             [Fact]
@@ -268,7 +268,7 @@ namespace Octokit.Tests.Clients
 
                 await client.Get("fake", "repo", "label");
 
-                connection.Received().Get<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels/label"), null, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels/label"));
             }
 
             [Fact]
@@ -279,7 +279,7 @@ namespace Octokit.Tests.Clients
 
                 await client.Get(1, "label");
 
-                connection.Received().Get<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels/label"), null, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels/label"));
             }
 
             [Fact]
@@ -313,7 +313,7 @@ namespace Octokit.Tests.Clients
 
                 client.AddToIssue("fake", "repo", 42, labels);
 
-                connection.Received().Post<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), Arg.Any<string[]>(), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Post<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), Arg.Any<string[]>());
             }
 
             [Fact]
@@ -324,7 +324,7 @@ namespace Octokit.Tests.Clients
 
                 client.AddToIssue(1, 42, labels);
 
-                connection.Received().Post<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Arg.Any<string[]>(), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Post<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Arg.Any<string[]>());
             }
 
             [Fact]
@@ -353,7 +353,7 @@ namespace Octokit.Tests.Clients
 
                 client.RemoveFromIssue("fake", "repo", 42, "label");
 
-                connection.Received().Delete<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels/label"), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Delete<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels/label"), Args.Object);
             }
 
             [Fact]
@@ -364,7 +364,7 @@ namespace Octokit.Tests.Clients
 
                 client.RemoveFromIssue(1, 42, "label");
 
-                connection.Received().Delete<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels/label"), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Delete<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels/label"), Args.Object);
             }
 
             [Fact]
@@ -398,7 +398,7 @@ namespace Octokit.Tests.Clients
 
                 client.ReplaceAllForIssue("fake", "repo", 42, labels);
 
-                connection.Received().Put<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), Arg.Any<string[]>(), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Put<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), Arg.Any<string[]>());
             }
 
             [Fact]
@@ -409,7 +409,7 @@ namespace Octokit.Tests.Clients
 
                 client.ReplaceAllForIssue(1, 42, labels);
 
-                connection.Received().Put<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Arg.Any<string[]>(), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Put<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Arg.Any<string[]>());
             }
 
             [Fact]
@@ -520,7 +520,7 @@ namespace Octokit.Tests.Clients
 
                 client.Create("fake", "repo", newLabel);
 
-                connection.Received().Post<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), newLabel, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Post<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), newLabel);
             }
 
             [Fact]
@@ -533,7 +533,7 @@ namespace Octokit.Tests.Clients
 
                 client.Create(1, newLabel);
 
-                connection.Received().Post<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), newLabel, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Post<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), newLabel);
             }
 
             [Fact]
@@ -565,7 +565,7 @@ namespace Octokit.Tests.Clients
 
                 client.Update("fake", "repo", "labelName", labelUpdate);
 
-                connection.Received().Post<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels/labelName"), labelUpdate, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Post<Label>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels/labelName"), labelUpdate);
             }
 
             [Fact]
@@ -578,7 +578,7 @@ namespace Octokit.Tests.Clients
 
                 client.Update(1, "labelName", labelUpdate);
 
-                connection.Received().Post<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels/labelName"), labelUpdate, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Post<Label>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels/labelName"), labelUpdate);
             }
 
             [Fact]
diff --git a/Octokit.Tests/Clients/MiscellaneousClientTests.cs b/Octokit.Tests/Clients/MiscellaneousClientTests.cs
index 08af9000..059316e3 100644
--- a/Octokit.Tests/Clients/MiscellaneousClientTests.cs
+++ b/Octokit.Tests/Clients/MiscellaneousClientTests.cs
@@ -201,7 +201,7 @@ namespace Octokit.Tests.Clients
                 });
 
                 var connection = Substitute.For<IApiConnection>();
-                connection.GetAll<LicenseMetadata>(Arg.Is<Uri>(u => u.ToString() == "licenses"), null, "application/vnd.github.drax-preview+json", Args.ApiOptions)
+                connection.GetAll<LicenseMetadata>(Arg.Is<Uri>(u => u.ToString() == "licenses"), Args.ApiOptions)
                     .Returns(Task.FromResult(response));
                 var client = new MiscellaneousClient(connection);
 
@@ -215,7 +215,7 @@ namespace Octokit.Tests.Clients
                 Assert.Equal("bar2", licenses[1].Name);
                 Assert.Equal("http://example.com/bar1", licenses[1].Url);
                 connection.Received()
-                    .GetAll<LicenseMetadata>(Arg.Is<Uri>(u => u.ToString() == "licenses"), null, AcceptHeaders.LicensesApiPreview, Args.ApiOptions);
+                    .GetAll<LicenseMetadata>(Arg.Is<Uri>(u => u.ToString() == "licenses"), Args.ApiOptions);
             }
         }
     }
diff --git a/Octokit.Tests/Clients/PullRequestsClientTests.cs b/Octokit.Tests/Clients/PullRequestsClientTests.cs
index fe0a4119..ca0488fc 100644
--- a/Octokit.Tests/Clients/PullRequestsClientTests.cs
+++ b/Octokit.Tests/Clients/PullRequestsClientTests.cs
@@ -332,8 +332,8 @@ namespace Octokit.Tests.Clients
 
                 client.Merge("fake", "repo", 42, mergePullRequest);
 
-                connection.Received().Put<PullRequestMerge>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/pulls/42/merge"),
-                    mergePullRequest, null, "application/vnd.github.polaris-preview+json");
+                connection.Received()
+                    .Put<PullRequestMerge>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/pulls/42/merge"), mergePullRequest);
             }
 
             [Fact]
@@ -345,8 +345,8 @@ namespace Octokit.Tests.Clients
 
                 client.Merge(1, 42, mergePullRequest);
 
-                connection.Received().Put<PullRequestMerge>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/pulls/42/merge"),
-                    mergePullRequest, null, "application/vnd.github.polaris-preview+json");
+                connection.Received()
+                    .Put<PullRequestMerge>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/pulls/42/merge"), mergePullRequest);
             }
 
             [Fact]
diff --git a/Octokit.Tests/Clients/RepoCollaboratorsClientTests.cs b/Octokit.Tests/Clients/RepoCollaboratorsClientTests.cs
index a4e7a5c1..73f6b35f 100644
--- a/Octokit.Tests/Clients/RepoCollaboratorsClientTests.cs
+++ b/Octokit.Tests/Clients/RepoCollaboratorsClientTests.cs
@@ -9,7 +9,7 @@ using Octokit.Internal;
 namespace Octokit.Tests.Clients
 {
     /// <summary>
-    /// Client tests mostly just need to make sure they call the IApiConnection with the correct 
+    /// Client tests mostly just need to make sure they call the IApiConnection with the correct
     /// relative Uri. No need to fake up the response. All *those* tests are in ApiConnectionTests.cs.
     /// </summary>
     public class RepoCollaboratorsClientTests
@@ -36,7 +36,6 @@ namespace Octokit.Tests.Clients
                 connection.Received().GetAll<User>(
                     Arg.Is<Uri>(u => u.ToString() == "repos/owner/test/collaborators"),
                     Arg.Any<Dictionary<string, string>>(),
-                    "application/vnd.github.hellcat-preview+json",
                     Args.ApiOptions);
             }
 
@@ -51,7 +50,6 @@ namespace Octokit.Tests.Clients
                 connection.Received().GetAll<User>(
                     Arg.Is<Uri>(u => u.ToString() == "repositories/1/collaborators"),
                     Arg.Any<Dictionary<string, string>>(),
-                    "application/vnd.github.hellcat-preview+json",
                     Args.ApiOptions);
             }
 
@@ -73,7 +71,6 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<User>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/test/collaborators"),
                         Arg.Any<Dictionary<string, string>>(),
-                        "application/vnd.github.hellcat-preview+json",
                         options);
             }
 
@@ -90,7 +87,6 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<User>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/test/collaborators"),
                         Arg.Is<Dictionary<string, string>>(d => d["affiliation"] == "all"),
-                        "application/vnd.github.hellcat-preview+json",
                         Args.ApiOptions);
 
                 request = new RepositoryCollaboratorListRequest
@@ -103,7 +99,6 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<User>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/test/collaborators"),
                         Arg.Is<Dictionary<string, string>>(d => d["affiliation"] == "direct"),
-                        "application/vnd.github.hellcat-preview+json",
                         Args.ApiOptions);
 
                 request = new RepositoryCollaboratorListRequest
@@ -116,7 +111,6 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<User>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/test/collaborators"),
                         Arg.Is<Dictionary<string, string>>(d => d["affiliation"] == "outside"),
-                        "application/vnd.github.hellcat-preview+json",
                         Args.ApiOptions);
             }
 
@@ -139,7 +133,6 @@ namespace Octokit.Tests.Clients
                     .GetAll<User>(
                         Arg.Is<Uri>(u => u.ToString() == "repositories/1/collaborators"),
                         Arg.Any<Dictionary<string, string>>(),
-                        "application/vnd.github.hellcat-preview+json",
                         options);
             }
 
@@ -157,7 +150,6 @@ namespace Octokit.Tests.Clients
                     .GetAll<User>(
                         Arg.Is<Uri>(u => u.ToString() == "repositories/1/collaborators"),
                         Arg.Is<Dictionary<string, string>>(d => d["affiliation"] == "all"),
-                        "application/vnd.github.hellcat-preview+json",
                         Args.ApiOptions);
 
                 request = new RepositoryCollaboratorListRequest
@@ -171,7 +163,6 @@ namespace Octokit.Tests.Clients
                     .GetAll<User>(
                         Arg.Is<Uri>(u => u.ToString() == "repositories/1/collaborators"),
                         Arg.Is<Dictionary<string, string>>(d => d["affiliation"] == "direct"),
-                        "application/vnd.github.hellcat-preview+json",
                         Args.ApiOptions);
 
                 request = new RepositoryCollaboratorListRequest
@@ -185,7 +176,6 @@ namespace Octokit.Tests.Clients
                     .GetAll<User>(
                         Arg.Is<Uri>(u => u.ToString() == "repositories/1/collaborators"),
                         Arg.Is<Dictionary<string, string>>(d => d["affiliation"] == "outside"),
-                        "application/vnd.github.hellcat-preview+json",
                         Args.ApiOptions);
             }
 
@@ -415,7 +405,7 @@ namespace Octokit.Tests.Clients
                 var permission = new CollaboratorRequest(Permission.Push);
 
                 client.Invite("owner", "test", "user1", permission);
-                connection.Received().Put<RepositoryInvitation>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/test/collaborators/user1"), Arg.Is<CollaboratorRequest>(permission), Arg.Any<string>(), Arg.Is<string>("application/vnd.github.swamp-thing-preview+json"));
+                connection.Received().Put<RepositoryInvitation>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/test/collaborators/user1"), Arg.Is<CollaboratorRequest>(permission));
             }
 
             [Fact]
diff --git a/Octokit.Tests/Clients/RepositoriesClientTests.cs b/Octokit.Tests/Clients/RepositoriesClientTests.cs
index fbca404f..56de5a76 100644
--- a/Octokit.Tests/Clients/RepositoriesClientTests.cs
+++ b/Octokit.Tests/Clients/RepositoriesClientTests.cs
@@ -8,7 +8,7 @@ using Xunit;
 namespace Octokit.Tests.Clients
 {
     /// <summary>
-    /// Client tests mostly just need to make sure they call the IApiConnection with the correct 
+    /// Client tests mostly just need to make sure they call the IApiConnection with the correct
     /// relative Uri. No need to fake up the response. All *those* tests are in ApiConnectionTests.cs.
     /// </summary>
     public class RepositoriesClientTests
@@ -266,8 +266,7 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .Post<Repository>(
                         Arg.Is<Uri>(u => u.ToString() == "repos/owner/name/transfer"),
-                        Arg.Any<RepositoryTransfer>(),
-                        Arg.Any<string>());
+                        Arg.Any<RepositoryTransfer>());
             }
 
             [Fact]
@@ -284,8 +283,7 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .Post<Repository>(
                         Arg.Is<Uri>(u => u.ToString() == "repositories/1/transfer"),
-                        Arg.Any<RepositoryTransfer>(),
-                        Arg.Any<string>());
+                        Arg.Any<RepositoryTransfer>());
             }
 
             [Fact]
@@ -301,9 +299,7 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .Post<Repository>(
                         Arg.Any<Uri>(),
-                        Arg.Is<RepositoryTransfer>(
-                            t => t.NewOwner == "newOwner" && object.Equals(teamId, t.TeamIds)),
-                        Arg.Any<string>());
+                        Arg.Is<RepositoryTransfer>(t => t.NewOwner == "newOwner" && object.Equals(teamId, t.TeamIds)));
             }
 
             [Fact]
@@ -320,9 +316,7 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .Post<Repository>(
                         Arg.Any<Uri>(),
-                        Arg.Is<RepositoryTransfer>(
-                            t => t.NewOwner == "newOwner" && object.Equals(teamId, t.TeamIds)),
-                        Arg.Any<string>());
+                        Arg.Is<RepositoryTransfer>(t => t.NewOwner == "newOwner" && object.Equals(teamId, t.TeamIds)));
             }
 
             [Fact]
@@ -338,9 +332,7 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .Post<Repository>(
                         Arg.Any<Uri>(),
-                        Arg.Any<RepositoryTransfer>(),
-                        Arg.Is<string>(
-                            s => s.Contains(AcceptHeaders.RepositoryTransferPreview)));
+                        Arg.Any<RepositoryTransfer>());
             }
 
             [Fact]
@@ -357,9 +349,8 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .Post<Repository>(
                         Arg.Any<Uri>(),
-                        Arg.Any<RepositoryTransfer>(),
-                        Arg.Is<string>(
-                            s => s.Contains(AcceptHeaders.RepositoryTransferPreview)));
+                        Arg.Any<RepositoryTransfer>())
+                        ;
             }
         }
 
@@ -410,10 +401,8 @@ namespace Octokit.Tests.Clients
 
                 await client.Get("owner", "name");
 
-                connection.Received().Get<Repository>(
-                    Arg.Is<Uri>(u => u.ToString() == "repos/owner/name"),
-                    null,
-                    "application/vnd.github.polaris-preview+json,application/vnd.github.drax-preview+json");
+                connection.Received()
+                    .Get<Repository>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/name"));
             }
 
             [Fact]
@@ -424,10 +413,8 @@ namespace Octokit.Tests.Clients
 
                 await client.Get(1);
 
-                connection.Received().Get<Repository>(
-                    Arg.Is<Uri>(u => u.ToString() == "repositories/1"),
-                    null,
-                    "application/vnd.github.polaris-preview+json,application/vnd.github.drax-preview+json");
+                connection.Received()
+                    .Get<Repository>(Arg.Is<Uri>(u => u.ToString() == "repositories/1"));
             }
 
             [Fact]
@@ -454,7 +441,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAllPublic();
 
                 connection.Received()
-                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "repositories"), null, "application/vnd.github.drax-preview+json");
+                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "repositories"));
             }
         }
 
@@ -469,7 +456,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAllPublic(new PublicRepositoryRequest(364L));
 
                 connection.Received()
-                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "repositories?since=364"), null, "application/vnd.github.drax-preview+json");
+                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "repositories?since=364"));
             }
 
             [Fact]
@@ -481,7 +468,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAllPublic(new PublicRepositoryRequest(364L));
 
                 connection.Received()
-                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "repositories?since=364"), null, "application/vnd.github.drax-preview+json");
+                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "repositories?since=364"));
             }
         }
 
@@ -496,7 +483,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAllForCurrent();
 
                 connection.Received()
-                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "user/repos"), null, "application/vnd.github.drax-preview+json", Args.ApiOptions);
+                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "user/repos"), Args.ApiOptions);
             }
 
             [Fact]
@@ -516,7 +503,6 @@ namespace Octokit.Tests.Clients
                     .GetAll<Repository>(
                         Arg.Is<Uri>(u => u.ToString() == "user/repos"),
                         Arg.Is<Dictionary<string, string>>(d => d["type"] == "all"),
-                        "application/vnd.github.drax-preview+json",
                         Args.ApiOptions);
             }
 
@@ -537,9 +523,7 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<Repository>(
                         Arg.Is<Uri>(u => u.ToString() == "user/repos"),
-                        Arg.Is<Dictionary<string, string>>(d =>
-                            d["type"] == "private" && d["sort"] == "full_name"),
-                        "application/vnd.github.drax-preview+json",
+                        Arg.Is<Dictionary<string, string>>(d => d["type"] == "private" && d["sort"] == "full_name"),
                         Args.ApiOptions);
             }
 
@@ -561,9 +545,7 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<Repository>(
                         Arg.Is<Uri>(u => u.ToString() == "user/repos"),
-                        Arg.Is<Dictionary<string, string>>(d =>
-                            d["type"] == "member" && d["sort"] == "updated" && d["direction"] == "asc"),
-                        "application/vnd.github.drax-preview+json",
+                        Arg.Is<Dictionary<string, string>>(d => d["type"] == "member" && d["sort"] == "updated" && d["direction"] == "asc"),
                         Args.ApiOptions);
             }
 
@@ -583,9 +565,7 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<Repository>(
                         Arg.Is<Uri>(u => u.ToString() == "user/repos"),
-                        Arg.Is<Dictionary<string, string>>(d =>
-                            d["visibility"] == "private"),
-                        "application/vnd.github.drax-preview+json",
+                        Arg.Is<Dictionary<string, string>>(d => d["visibility"] == "private"),
                         Args.ApiOptions);
             }
 
@@ -606,9 +586,7 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<Repository>(
                         Arg.Is<Uri>(u => u.ToString() == "user/repos"),
-                        Arg.Is<Dictionary<string, string>>(d =>
-                            d["affiliation"] == "owner" && d["sort"] == "full_name"),
-                        "application/vnd.github.drax-preview+json",
+                        Arg.Is<Dictionary<string, string>>(d => d["affiliation"] == "owner" && d["sort"] == "full_name"),
                         Args.ApiOptions);
             }
         }
@@ -624,7 +602,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAllForUser("username");
 
                 connection.Received()
-                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "users/username/repos"), null, "application/vnd.github.drax-preview+json", Args.ApiOptions);
+                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "users/username/repos"), Args.ApiOptions);
             }
 
             [Fact]
@@ -653,7 +631,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAllForOrg("orgname");
 
                 connection.Received()
-                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "orgs/orgname/repos"), null, "application/vnd.github.drax-preview+json", Args.ApiOptions);
+                    .GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "orgs/orgname/repos"), Args.ApiOptions);
             }
 
             [Fact]
@@ -874,8 +852,6 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<Team>(
                         Arg.Is<Uri>(u => u.ToString() == "repos/owner/name/teams"),
-                        null,
-                        "application/vnd.github.hellcat-preview+json",
                         Args.ApiOptions);
             }
 
@@ -911,8 +887,6 @@ namespace Octokit.Tests.Clients
                 connection.Received()
                     .GetAll<Team>(
                         Arg.Is<Uri>(u => u.ToString() == "repos/owner/name/teams"),
-                        null,
-                        "application/vnd.github.hellcat-preview+json",
                         options);
             }
 
@@ -968,7 +942,7 @@ namespace Octokit.Tests.Clients
                 await client.GetLicenseContents("owner", "name");
 
                 connection.Received()
-                    .Get<RepositoryContentLicense>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/name/license"), null, "application/vnd.github.drax-preview+json");
+                    .Get<RepositoryContentLicense>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/name/license"));
             }
 
             [Fact]
@@ -980,7 +954,7 @@ namespace Octokit.Tests.Clients
                 await client.GetLicenseContents(1);
 
                 connection.Received()
-                    .Get<RepositoryContentLicense>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/license"), null, "application/vnd.github.drax-preview+json");
+                    .Get<RepositoryContentLicense>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/license"));
             }
 
             [Fact]
@@ -1089,7 +1063,7 @@ namespace Octokit.Tests.Clients
                 client.Edit("owner", "repo", update);
 
                 connection.Received()
-                    .Patch<Repository>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo"), Arg.Any<RepositoryUpdate>(), "application/vnd.github.polaris-preview+json,application/vnd.github.drax-preview+json");
+                    .Patch<Repository>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo"), Arg.Any<RepositoryUpdate>());
             }
 
             [Fact]
@@ -1102,7 +1076,7 @@ namespace Octokit.Tests.Clients
                 client.Edit(1, update);
 
                 connection.Received()
-                    .Patch<Repository>(Arg.Is<Uri>(u => u.ToString() == "repositories/1"), Arg.Any<RepositoryUpdate>(), "application/vnd.github.polaris-preview+json,application/vnd.github.drax-preview+json");
+                    .Patch<Repository>(Arg.Is<Uri>(u => u.ToString() == "repositories/1"), Arg.Any<RepositoryUpdate>());
             }
 
             [Fact]
diff --git a/Octokit.Tests/Clients/RepositoryBranchesClientTests.cs b/Octokit.Tests/Clients/RepositoryBranchesClientTests.cs
index 40a5602a..267bf4e1 100644
--- a/Octokit.Tests/Clients/RepositoryBranchesClientTests.cs
+++ b/Octokit.Tests/Clients/RepositoryBranchesClientTests.cs
@@ -8,7 +8,7 @@ using Xunit;
 namespace Octokit.Tests.Clients
 {
     /// <summary>
-    /// Client tests mostly just need to make sure they call the IApiConnection with the correct 
+    /// Client tests mostly just need to make sure they call the IApiConnection with the correct
     /// relative Uri. No need to fake up the response. All *those* tests are in ApiConnectionTests.cs.
     /// </summary>
     public class RepositoryBranchesClientTests
@@ -33,7 +33,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAll("owner", "name");
 
                 connection.Received()
-                    .GetAll<Branch>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/name/branches"), null, "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json", Args.ApiOptions);
+                    .GetAll<Branch>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/name/branches"), null, "application/vnd.github.luke-cage-preview+json", Args.ApiOptions);
             }
 
             [Fact]
@@ -45,7 +45,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAll(1);
 
                 connection.Received()
-                    .GetAll<Branch>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches"), null, "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json", Args.ApiOptions);
+                    .GetAll<Branch>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches"), null, "application/vnd.github.luke-cage-preview+json", Args.ApiOptions);
             }
 
             [Fact]
@@ -64,7 +64,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAll("owner", "name", options);
 
                 connection.Received()
-                    .GetAll<Branch>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/name/branches"), null, "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json", options);
+                    .GetAll<Branch>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/name/branches"), null, "application/vnd.github.luke-cage-preview+json", options);
             }
 
             [Fact]
@@ -83,7 +83,7 @@ namespace Octokit.Tests.Clients
                 await client.GetAll(1, options);
 
                 connection.Received()
-                    .GetAll<Branch>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches"), null, "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json", options);
+                    .GetAll<Branch>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches"), null, "application/vnd.github.luke-cage-preview+json", options);
             }
 
             [Fact]
@@ -118,7 +118,7 @@ namespace Octokit.Tests.Clients
                 await client.Get("owner", "repo", "branch");
 
                 connection.Received()
-                    .Get<Branch>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/branches/branch"), null, "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json");
+                    .Get<Branch>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/branches/branch"), null, "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -130,7 +130,7 @@ namespace Octokit.Tests.Clients
                 await client.Get(1, "branch");
 
                 connection.Received()
-                    .Get<Branch>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches/branch"), null, "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json");
+                    .Get<Branch>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches/branch"), null, "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -157,7 +157,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetBranchProtection("owner", "repo", "branch");
 
@@ -170,7 +170,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetBranchProtection(1, "branch");
 
@@ -206,7 +206,7 @@ namespace Octokit.Tests.Clients
                 var client = new RepositoryBranchesClient(connection);
                 var update = new BranchProtectionSettingsUpdate(
                     new BranchProtectionRequiredStatusChecksUpdate(true, new[] { "test" }));
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateBranchProtection("owner", "repo", "branch", update);
 
@@ -221,7 +221,7 @@ namespace Octokit.Tests.Clients
                 var client = new RepositoryBranchesClient(connection);
                 var update = new BranchProtectionSettingsUpdate(
                     new BranchProtectionRequiredStatusChecksUpdate(true, new[] { "test" }));
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateBranchProtection(1, "branch", update);
 
@@ -259,7 +259,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteBranchProtection("owner", "repo", "branch");
 
@@ -272,7 +272,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteBranchProtection(1, "branch");
 
@@ -306,7 +306,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetRequiredStatusChecks("owner", "repo", "branch");
 
@@ -319,7 +319,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetRequiredStatusChecks(1, "branch");
 
@@ -354,7 +354,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var update = new BranchProtectionRequiredStatusChecksUpdate(true, new[] { "test" });
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateRequiredStatusChecks("owner", "repo", "branch", update);
 
@@ -368,7 +368,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var update = new BranchProtectionRequiredStatusChecksUpdate(true, new[] { "test" });
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateRequiredStatusChecks(1, "branch", update);
 
@@ -405,7 +405,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteRequiredStatusChecks("owner", "repo", "branch");
 
@@ -418,7 +418,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteRequiredStatusChecks(1, "branch");
 
@@ -452,7 +452,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetAllRequiredStatusChecksContexts("owner", "repo", "branch");
 
@@ -465,7 +465,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetAllRequiredStatusChecksContexts(1, "branch");
 
@@ -500,7 +500,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var update = new List<string>() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateRequiredStatusChecksContexts("owner", "repo", "branch", update);
 
@@ -514,7 +514,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var update = new List<string>() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateRequiredStatusChecksContexts(1, "branch", update);
 
@@ -552,7 +552,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var newContexts = new List<string>() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.AddRequiredStatusChecksContexts("owner", "repo", "branch", newContexts);
 
@@ -566,7 +566,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var newContexts = new List<string>() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.AddRequiredStatusChecksContexts(1, "branch", newContexts);
 
@@ -604,7 +604,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var contextsToRemove = new List<string>() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteRequiredStatusChecksContexts("owner", "repo", "branch", contextsToRemove);
 
@@ -618,7 +618,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var contextsToRemove = new List<string>() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteRequiredStatusChecksContexts(1, "branch", contextsToRemove);
 
@@ -655,7 +655,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetReviewEnforcement("owner", "repo", "branch");
 
@@ -668,7 +668,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetReviewEnforcement(1, "branch");
 
@@ -703,7 +703,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var update = new BranchProtectionRequiredReviewsUpdate(false, false, 2);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateReviewEnforcement("owner", "repo", "branch", update);
 
@@ -717,7 +717,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var update = new BranchProtectionRequiredReviewsUpdate(false, false, 2);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateReviewEnforcement(1, "branch", update);
 
@@ -755,7 +755,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.RemoveReviewEnforcement("owner", "repo", "branch");
 
@@ -768,7 +768,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.RemoveReviewEnforcement(1, "branch");
 
@@ -802,7 +802,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetAdminEnforcement("owner", "repo", "branch");
 
@@ -815,7 +815,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetAdminEnforcement(1, "branch");
 
@@ -849,7 +849,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.AddAdminEnforcement("owner", "repo", "branch");
 
@@ -862,7 +862,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.AddAdminEnforcement(1, "branch");
 
@@ -896,7 +896,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.RemoveAdminEnforcement("owner", "repo", "branch");
 
@@ -909,7 +909,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.RemoveAdminEnforcement(1, "branch");
 
@@ -943,7 +943,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetProtectedBranchRestrictions("owner", "repo", "branch");
 
@@ -956,7 +956,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetProtectedBranchRestrictions(1, "branch");
 
@@ -990,7 +990,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteProtectedBranchRestrictions("owner", "repo", "branch");
 
@@ -1003,7 +1003,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteProtectedBranchRestrictions(1, "branch");
 
@@ -1044,7 +1044,7 @@ namespace Octokit.Tests.Clients
                     .Get<IReadOnlyList<Team>>(
                     Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/branches/branch/protection/restrictions/teams"),
                     null,
-                    "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json,application/vnd.github.hellcat-preview+json");
+                    "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -1059,7 +1059,7 @@ namespace Octokit.Tests.Clients
                     .Get<IReadOnlyList<Team>>(
                     Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches/branch/protection/restrictions/teams"),
                     null,
-                    "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json,application/vnd.github.hellcat-preview+json");
+                    "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -1097,7 +1097,7 @@ namespace Octokit.Tests.Clients
                     Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/branches/branch/protection/restrictions/teams"),
                     Arg.Any<IReadOnlyList<string>>(),
                     null,
-                    "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json,application/vnd.github.hellcat-preview+json");
+                    "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -1114,7 +1114,7 @@ namespace Octokit.Tests.Clients
                         Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches/branch/protection/restrictions/teams"),
                         Arg.Any<IReadOnlyList<string>>(),
                         null,
-                        "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json,application/vnd.github.hellcat-preview+json");
+                        "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -1154,7 +1154,7 @@ namespace Octokit.Tests.Clients
                     .Post<IReadOnlyList<Team>>(
                         Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/branches/branch/protection/restrictions/teams"),
                         Arg.Any<IReadOnlyList<string>>(),
-                        "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json,application/vnd.github.hellcat-preview+json");
+                        "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -1170,7 +1170,7 @@ namespace Octokit.Tests.Clients
                     .Post<IReadOnlyList<Team>>(
                         Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches/branch/protection/restrictions/teams"),
                         Arg.Any<IReadOnlyList<string>>(),
-                        "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json,application/vnd.github.hellcat-preview+json");
+                        "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -1210,7 +1210,7 @@ namespace Octokit.Tests.Clients
                     .Delete<IReadOnlyList<Team>>(
                         Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/branches/branch/protection/restrictions/teams"),
                         Arg.Any<BranchProtectionTeamCollection>(),
-                        "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json,application/vnd.github.hellcat-preview+json");
+                        "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -1226,7 +1226,7 @@ namespace Octokit.Tests.Clients
                     .Delete<IReadOnlyList<Team>>(
                         Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches/branch/protection/restrictions/teams"),
                         Arg.Any<IReadOnlyList<string>>(),
-                        "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json,application/vnd.github.hellcat-preview+json");
+                        "application/vnd.github.luke-cage-preview+json");
             }
 
             [Fact]
@@ -1258,7 +1258,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetAllProtectedBranchUserRestrictions("owner", "repo", "branch");
 
@@ -1271,7 +1271,7 @@ namespace Octokit.Tests.Clients
             {
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.GetAllProtectedBranchUserRestrictions(1, "branch");
 
@@ -1306,7 +1306,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var newUsers = new BranchProtectionUserCollection() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateProtectedBranchUserRestrictions("owner", "repo", "branch", newUsers);
 
@@ -1320,7 +1320,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var newUsers = new BranchProtectionUserCollection() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.UpdateProtectedBranchUserRestrictions(1, "branch", newUsers);
 
@@ -1358,7 +1358,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var newUsers = new BranchProtectionUserCollection() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.AddProtectedBranchUserRestrictions("owner", "repo", "branch", newUsers);
 
@@ -1372,7 +1372,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var newUsers = new BranchProtectionUserCollection() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.AddProtectedBranchUserRestrictions(1, "branch", newUsers);
 
@@ -1410,7 +1410,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var usersToRemove = new BranchProtectionUserCollection() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteProtectedBranchUserRestrictions("owner", "repo", "branch", usersToRemove);
 
@@ -1424,7 +1424,7 @@ namespace Octokit.Tests.Clients
                 var connection = Substitute.For<IApiConnection>();
                 var client = new RepositoryBranchesClient(connection);
                 var usersToRemove = new BranchProtectionUserCollection() { "test" };
-                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json,application/vnd.github.luke-cage-preview+json";
+                const string previewAcceptsHeader = "application/vnd.github.luke-cage-preview+json";
 
                 client.DeleteProtectedBranchUserRestrictions(1, "branch", usersToRemove);
 
diff --git a/Octokit.Tests/Clients/RepositoryInvitationsClientTests.cs b/Octokit.Tests/Clients/RepositoryInvitationsClientTests.cs
index cfb23c44..50b62387 100644
--- a/Octokit.Tests/Clients/RepositoryInvitationsClientTests.cs
+++ b/Octokit.Tests/Clients/RepositoryInvitationsClientTests.cs
@@ -35,7 +35,7 @@ public class RepositoryInvitationsClientTests
 
             await client.GetAllForRepository(1);
 
-            connection.Received().GetAll<RepositoryInvitation>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/invitations"), null, "application/vnd.github.swamp-thing-preview+json", Args.ApiOptions);
+            connection.Received().GetAll<RepositoryInvitation>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/invitations"), Args.ApiOptions);
         }
     }
 
@@ -58,7 +58,7 @@ public class RepositoryInvitationsClientTests
 
             await client.GetAllForCurrent();
 
-            connection.Received().GetAll<RepositoryInvitation>(Arg.Is<Uri>(u => u.ToString() == "user/repository_invitations"), null, "application/vnd.github.swamp-thing-preview+json", Args.ApiOptions);
+            connection.Received().GetAll<RepositoryInvitation>(Arg.Is<Uri>(u => u.ToString() == "user/repository_invitations"), Args.ApiOptions);
         }
     }
 
@@ -72,7 +72,7 @@ public class RepositoryInvitationsClientTests
 
             await client.Accept(1);
 
-            connection.Connection.Received().Patch(Arg.Is<Uri>(u => u.ToString() == "user/repository_invitations/1"), "application/vnd.github.swamp-thing-preview+json");
+            connection.Connection.Received().Patch(Arg.Is<Uri>(u => u.ToString() == "user/repository_invitations/1"));
         }
     }
 
@@ -86,7 +86,7 @@ public class RepositoryInvitationsClientTests
 
             await client.Decline(1);
 
-            connection.Connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == "user/repository_invitations/1"), Arg.Any<object>(), "application/vnd.github.swamp-thing-preview+json");
+            connection.Connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == "user/repository_invitations/1"));
         }
     }
 
@@ -100,7 +100,7 @@ public class RepositoryInvitationsClientTests
 
             await client.Delete(1, 2);
 
-            connection.Connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == "repositories/1/invitations/2"), Arg.Any<object>(), "application/vnd.github.swamp-thing-preview+json");
+            connection.Connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == "repositories/1/invitations/2"));
         }
     }
 
@@ -115,7 +115,7 @@ public class RepositoryInvitationsClientTests
 
             await client.Edit(1, 2, updatedInvitation);
 
-            connection.Received().Patch<RepositoryInvitation>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/invitations/2"), Arg.Is<InvitationUpdate>(updatedInvitation), "application/vnd.github.swamp-thing-preview+json");
+            connection.Received().Patch<RepositoryInvitation>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/invitations/2"), Arg.Is<InvitationUpdate>(updatedInvitation));
         }
 
         [Fact]
@@ -127,4 +127,3 @@ public class RepositoryInvitationsClientTests
         }
     }
 }
-
diff --git a/Octokit.Tests/Clients/RepositoryPagesClientTests.cs b/Octokit.Tests/Clients/RepositoryPagesClientTests.cs
index 0e7fbfcf..2abbd1ae 100644
--- a/Octokit.Tests/Clients/RepositoryPagesClientTests.cs
+++ b/Octokit.Tests/Clients/RepositoryPagesClientTests.cs
@@ -180,7 +180,7 @@ namespace Octokit.Tests.Clients
 
                 await client.RequestPageBuild("fake", "repo");
 
-                connection.Received().Post<PagesBuild>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/pages/builds"), "application/vnd.github.mister-fantastic-preview+json");
+                connection.Received().Post<PagesBuild>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/pages/builds"));
             }
 
             [Fact]
@@ -191,7 +191,7 @@ namespace Octokit.Tests.Clients
 
                 await client.RequestPageBuild(1);
 
-                connection.Received().Post<PagesBuild>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/pages/builds"), "application/vnd.github.mister-fantastic-preview+json");
+                connection.Received().Post<PagesBuild>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/pages/builds"));
             }
 
             [Fact]
diff --git a/Octokit.Tests/Clients/RepositoryTrafficClientTests.cs b/Octokit.Tests/Clients/RepositoryTrafficClientTests.cs
index cdea820f..2e13ae7b 100644
--- a/Octokit.Tests/Clients/RepositoryTrafficClientTests.cs
+++ b/Octokit.Tests/Clients/RepositoryTrafficClientTests.cs
@@ -28,7 +28,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllReferrers("fake", "repo");
 
-                connection.Received().GetAll<RepositoryTrafficReferrer>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/traffic/popular/referrers"), "application/vnd.github.spiderman-preview");
+                connection.Received().GetAll<RepositoryTrafficReferrer>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/traffic/popular/referrers"));
             }
 
             [Fact]
@@ -39,7 +39,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllReferrers(1);
 
-                connection.Received().GetAll<RepositoryTrafficReferrer>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/traffic/popular/referrers"), "application/vnd.github.spiderman-preview");
+                connection.Received().GetAll<RepositoryTrafficReferrer>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/traffic/popular/referrers"));
             }
 
             [Fact]
@@ -65,7 +65,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllPaths("fake", "repo");
 
-                connection.Received().GetAll<RepositoryTrafficPath>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/traffic/popular/paths"), "application/vnd.github.spiderman-preview");
+                connection.Received().GetAll<RepositoryTrafficPath>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/traffic/popular/paths"));
             }
 
             [Fact]
@@ -76,7 +76,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetAllPaths(1);
 
-                connection.Received().GetAll<RepositoryTrafficPath>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/traffic/popular/paths"), "application/vnd.github.spiderman-preview");
+                connection.Received().GetAll<RepositoryTrafficPath>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/traffic/popular/paths"));
             }
 
             [Fact]
@@ -103,7 +103,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetClones("fake", "repo", per);
 
-                connection.Received().Get<RepositoryTrafficCloneSummary>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/traffic/clones"), Arg.Is<Dictionary<string, string>>(s => s["per"] == "day"), "application/vnd.github.spiderman-preview");
+                connection.Received().Get<RepositoryTrafficCloneSummary>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/traffic/clones"), Arg.Is<Dictionary<string, string>>(s => s["per"] == "day"));
             }
 
             [Fact]
@@ -115,7 +115,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetClones(1, per);
 
-                connection.Received().Get<RepositoryTrafficCloneSummary>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/traffic/clones"), Arg.Is<Dictionary<string, string>>(s => s["per"] == "day"), "application/vnd.github.spiderman-preview");
+                connection.Received().Get<RepositoryTrafficCloneSummary>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/traffic/clones"), Arg.Is<Dictionary<string, string>>(s => s["per"] == "day"));
             }
 
             [Fact]
@@ -146,7 +146,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetViews("fake", "repo", per);
 
-                connection.Received().Get<RepositoryTrafficViewSummary>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/traffic/views"), Arg.Is<Dictionary<string, string>>(s => s["per"] == "day"), "application/vnd.github.spiderman-preview");
+                connection.Received().Get<RepositoryTrafficViewSummary>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/traffic/views"), Arg.Is<Dictionary<string, string>>(s => s["per"] == "day"));
             }
 
             [Fact]
@@ -158,7 +158,7 @@ namespace Octokit.Tests.Clients
 
                 await client.GetViews(1, per);
 
-                connection.Received().Get<RepositoryTrafficViewSummary>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/traffic/views"), Arg.Is<Dictionary<string, string>>(s => s["per"] == "day"), "application/vnd.github.spiderman-preview");
+                connection.Received().Get<RepositoryTrafficViewSummary>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/traffic/views"), Arg.Is<Dictionary<string, string>>(s => s["per"] == "day"));
             }
 
             [Fact]
diff --git a/Octokit.Tests/Clients/SearchClientTests.cs b/Octokit.Tests/Clients/SearchClientTests.cs
index fc6eafe1..e9fc20ac 100644
--- a/Octokit.Tests/Clients/SearchClientTests.cs
+++ b/Octokit.Tests/Clients/SearchClientTests.cs
@@ -7,7 +7,7 @@ using System.Threading.Tasks;
 namespace Octokit.Tests.Clients
 {
     /// <summary>
-    /// Client tests mostly just need to make sure they call the IApiConnection with the correct 
+    /// Client tests mostly just need to make sure they call the IApiConnection with the correct
     /// relative Uri. No need to fake up the response. All *those* tests are in ApiConnectionTests.cs.
     /// </summary>
     public class SearchClientTests
@@ -1936,8 +1936,7 @@ namespace Octokit.Tests.Clients
                 client.SearchLabels(new SearchLabelsRequest("something", 1));
                 connection.Received().Get<SearchLabelsResult>(
                     Arg.Is<Uri>(u => u.ToString() == "search/labels"),
-                    Arg.Any<Dictionary<string, string>>(),
-                    "application/vnd.github.symmetra-preview+json");
+                    Arg.Any<Dictionary<string, string>>());
             }
 
             [Fact]
@@ -1960,8 +1959,7 @@ namespace Octokit.Tests.Clients
                     Arg.Is<Uri>(u => u.ToString() == "search/labels"),
                     Arg.Is<Dictionary<string, string>>(d =>
                         d["q"] == "something" &&
-                        d["repository_id"] == "1"),
-                    "application/vnd.github.symmetra-preview+json");
+                        d["repository_id"] == "1"));
             }
 
             [Fact]
@@ -1976,8 +1974,7 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().Get<SearchLabelsResult>(
                     Arg.Is<Uri>(u => u.ToString() == "search/labels"),
-                    Arg.Is<Dictionary<string, string>>(d => d["sort"] == "created"),
-                    "application/vnd.github.symmetra-preview+json");
+                    Arg.Is<Dictionary<string, string>>(d => d["sort"] == "created"));
             }
 
             [Fact]
@@ -1995,8 +1992,7 @@ namespace Octokit.Tests.Clients
                     Arg.Is<Uri>(u => u.ToString() == "search/labels"),
                     Arg.Is<Dictionary<string, string>>(d =>
                         d["sort"] == "created" &&
-                        d["order"] == "asc"),
-                    "application/vnd.github.symmetra-preview+json");
+                        d["order"] == "asc"));
             }
 
             [Fact]
@@ -2010,8 +2006,7 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().Get<SearchLabelsResult>(
                     Arg.Is<Uri>(u => u.ToString() == "search/labels"),
-                    Arg.Is<Dictionary<string, string>>(d => d["order"] == "desc"),
-                    "application/vnd.github.symmetra-preview+json");
+                    Arg.Is<Dictionary<string, string>>(d => d["order"] == "desc"));
             }
 
             [Fact]
@@ -2027,9 +2022,8 @@ namespace Octokit.Tests.Clients
                     Arg.Is<Uri>(u => u.ToString() == "search/labels"),
                     Arg.Is<Dictionary<string, string>>(d =>
                         d["q"] == "something" &&
-                        d["repository_id"] == "1"),
-                    "application/vnd.github.symmetra-preview+json");
+                        d["repository_id"] == "1"));
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Octokit.Tests/Clients/TagsClientTests.cs b/Octokit.Tests/Clients/TagsClientTests.cs
index ec697e7a..ec864f52 100644
--- a/Octokit.Tests/Clients/TagsClientTests.cs
+++ b/Octokit.Tests/Clients/TagsClientTests.cs
@@ -18,7 +18,7 @@ public class TagsClientTests
 
             await client.Get("owner", "repo", "reference");
 
-            connection.Received().Get<GitTag>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/git/tags/reference"), null, "application/vnd.github.cryptographer-preview+sha");
+            connection.Received().Get<GitTag>(Arg.Is<Uri>(u => u.ToString() == "repos/owner/repo/git/tags/reference"));
         }
 
         [Fact]
@@ -29,7 +29,7 @@ public class TagsClientTests
 
             await client.Get(1, "reference");
 
-            connection.Received().Get<GitTag>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/git/tags/reference"), null, "application/vnd.github.cryptographer-preview+sha");
+            connection.Received().Get<GitTag>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/git/tags/reference"));
         }
 
         [Fact]
diff --git a/Octokit.Tests/Clients/TeamsClientTests.cs b/Octokit.Tests/Clients/TeamsClientTests.cs
index 09f53dc1..ab2cad0d 100644
--- a/Octokit.Tests/Clients/TeamsClientTests.cs
+++ b/Octokit.Tests/Clients/TeamsClientTests.cs
@@ -8,7 +8,7 @@ using Xunit;
 namespace Octokit.Tests.Clients
 {
     /// <summary>
-    /// Client tests mostly just need to make sure they call the IApiConnection with the correct 
+    /// Client tests mostly just need to make sure they call the IApiConnection with the correct
     /// relative Uri. No need to fake up the response. All *those* tests are in ApiConnectionTests.cs.
     /// </summary>
     public class TeamsClientTests
@@ -33,9 +33,7 @@ namespace Octokit.Tests.Clients
                 client.Get(1);
 
                 connection.Received().Get<Team>(
-                    Arg.Is<Uri>(u => u.ToString() == "teams/1"),
-                    null,
-                    "application/vnd.github.hellcat-preview+json");
+                    Arg.Is<Uri>(u => u.ToString() == "teams/1"));
             }
         }
 
@@ -51,8 +49,6 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().GetAll<Team>(
                     Arg.Is<Uri>(u => u.ToString() == "orgs/orgName/teams"),
-                    null,
-                    "application/vnd.github.hellcat-preview+json",
                     Args.ApiOptions);
             }
 
@@ -78,8 +74,6 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().GetAll<Team>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1/teams"),
-                    null,
-                    "application/vnd.github.hellcat-preview+json",
                     Args.ApiOptions);
             }
 
@@ -105,8 +99,6 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().GetAll<User>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1/members"),
-                    null,
-                    "application/vnd.github.hellcat-preview+json",
                     Args.ApiOptions);
             }
 
@@ -121,7 +113,6 @@ namespace Octokit.Tests.Clients
                 connection.Received().GetAll<User>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1/members"),
                     Arg.Is<Dictionary<string, string>>(d => d["role"] == "maintainer"),
-                    "application/vnd.github.hellcat-preview+json",
                     Args.ApiOptions);
             }
 
@@ -153,8 +144,7 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().Post<Team>(
                     Arg.Is<Uri>(u => u.ToString() == "orgs/orgName/teams"),
-                    team,
-                    "application/vnd.github.hellcat-preview+json");
+                    team);
             }
 
             [Fact]
@@ -183,8 +173,7 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().Patch<Team>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1"),
-                    team,
-                    "application/vnd.github.hellcat-preview+json");
+                    team);
             }
 
             [Fact]
@@ -207,9 +196,7 @@ namespace Octokit.Tests.Clients
                 client.Delete(1);
 
                 connection.Received().Delete(
-                    Arg.Is<Uri>(u => u.ToString() == "teams/1"),
-                    Args.Object,
-                    "application/vnd.github.hellcat-preview+json");
+                    Arg.Is<Uri>(u => u.ToString() == "teams/1"));
             }
         }
 
@@ -255,8 +242,6 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().GetAll<Team>(
                     Arg.Is<Uri>(u => u.ToString() == "user/teams"),
-                    null,
-                    "application/vnd.github.hellcat-preview+json",
                     Args.ApiOptions);
             }
         }
@@ -271,9 +256,7 @@ namespace Octokit.Tests.Clients
                 await client.GetMembershipDetails(1, "user");
 
                 connection.Received().Get<TeamMembershipDetails>(
-                    Arg.Is<Uri>(u => u.ToString() == "teams/1/memberships/user"),
-                    null,
-                    "application/vnd.github.hellcat-preview+json");
+                    Arg.Is<Uri>(u => u.ToString() == "teams/1/memberships/user"));
             }
 
             [Fact]
@@ -298,9 +281,7 @@ namespace Octokit.Tests.Clients
                 await client.RemoveMembership(1, "user");
 
                 connection.Connection.Received().Delete(
-                    Arg.Is<Uri>(u => u.ToString() == "teams/1/memberships/user"),
-                    Arg.Any<object>(),
-                    "application/vnd.github.hellcat-preview+json");
+                    Arg.Is<Uri>(u => u.ToString() == "teams/1/memberships/user"));
             }
 
             [Fact]
@@ -326,8 +307,6 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().GetAll<Repository>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1/repos"),
-                    null,
-                    "application/vnd.github.hellcat-preview+json",
                     Args.ApiOptions);
             }
         }
@@ -371,8 +350,7 @@ namespace Octokit.Tests.Clients
                 await client.AddRepository(1, "org", "repo");
 
                 connection.Connection.Received().Put(
-                    Arg.Is<Uri>(u => u.ToString() == "teams/1/repos/org/repo"),
-                    "application/vnd.github.hellcat-preview+json");
+                    Arg.Is<Uri>(u => u.ToString() == "teams/1/repos/org/repo"));
             }
 
             [Fact]
@@ -386,9 +364,7 @@ namespace Octokit.Tests.Clients
 
                 connection.Connection.Received().Put<HttpStatusCode>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1/repos/org/repo"),
-                    Arg.Any<object>(),
-                    "",
-                    "application/vnd.github.hellcat-preview+json");
+                    newPermission);
             }
 
             [Fact]
diff --git a/Octokit.Tests/Clients/UserGpgKeysClientTests.cs b/Octokit.Tests/Clients/UserGpgKeysClientTests.cs
index bc9a9891..dfc32a07 100644
--- a/Octokit.Tests/Clients/UserGpgKeysClientTests.cs
+++ b/Octokit.Tests/Clients/UserGpgKeysClientTests.cs
@@ -32,8 +32,6 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().GetAll<GpgKey>(
                     Arg.Is<Uri>(u => u.ToString() == expectedUri),
-                    Arg.Any<Dictionary<string, string>>(),
-                    Arg.Is<string>(s => s == "application/vnd.github.cryptographer-preview"),
                     Arg.Any<ApiOptions>());
             }
         }
@@ -49,10 +47,7 @@ namespace Octokit.Tests.Clients
                 var expectedUri = "user/gpg_keys/1";
                 client.Get(1);
 
-                connection.Received().Get<GpgKey>(
-                    Arg.Is<Uri>(u => u.ToString() == expectedUri),
-                    Arg.Any<Dictionary<string, string>>(),
-                    Arg.Is<string>(s => s == "application/vnd.github.cryptographer-preview"));
+                connection.Received().Get<GpgKey>(Arg.Is<Uri>(u => u.ToString() == expectedUri));
             }
         }
 
@@ -76,8 +71,7 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().Post<GpgKey>(
                     Arg.Is<Uri>(u => u.ToString() == expectedUri),
-                    Arg.Any<object>(),
-                    Arg.Is<string>(s => s == "application/vnd.github.cryptographer-preview"));
+                    Arg.Any<object>());
             }
 
             [Fact]
@@ -91,9 +85,7 @@ namespace Octokit.Tests.Clients
 
                 connection.Received().Post<GpgKey>(
                     Arg.Is<Uri>(u => u.ToString() == expectedUri),
-                    Arg.Is<NewGpgKey>(a =>
-                        a.ArmoredPublicKey == "ABCDEFG"),
-                    Arg.Any<string>());
+                    Arg.Is<NewGpgKey>(a => a.ArmoredPublicKey == "ABCDEFG"));
             }
         }
 
@@ -108,10 +100,7 @@ namespace Octokit.Tests.Clients
                 var expectedUri = "user/gpg_keys/1";
                 client.Delete(1);
 
-                connection.Received().Delete(
-                    Arg.Is<Uri>(u => u.ToString() == expectedUri),
-                    Arg.Any<object>(),
-                    Arg.Is<string>(s => s == "application/vnd.github.cryptographer-preview"));
+                connection.Received().Delete(Arg.Is<Uri>(u => u.ToString() == expectedUri));
             }
         }
     }
diff --git a/Octokit.Tests/Http/ConnectionTests.cs b/Octokit.Tests/Http/ConnectionTests.cs
index 2f1edef9..3bca0373 100644
--- a/Octokit.Tests/Http/ConnectionTests.cs
+++ b/Octokit.Tests/Http/ConnectionTests.cs
@@ -396,7 +396,7 @@ namespace Octokit.Tests.Http
                     req.ContentType == null &&
                     req.Body == null &&
                     req.Method == HttpMethod.Get &&
-                    req.Headers["Accept"] == "application/vnd.github.html" &&
+                    req.Headers["Accept"] == "application/vnd.github.v3.html" &&
                     req.Endpoint == new Uri("endpoint", UriKind.Relative)), Args.CancellationToken);
             }
         }
@@ -631,7 +631,7 @@ namespace Octokit.Tests.Http
                 httpClient.Received().Send(Arg.Is<IRequest>(req =>
                     req.BaseAddress == _exampleUri &&
                     req.Body == body &&
-                    req.Headers["Accept"] == "application/vnd.github.quicksilver-preview+json; charset=utf-8, application/vnd.github.v3+json; charset=utf-8" &&
+                    req.Headers["Accept"] == "application/vnd.github.v3+json" &&
                     req.ContentType == "application/arbitrary" &&
                     req.Method == HttpMethod.Post &&
                     req.Endpoint == new Uri("https://other.host.com/path?query=val")), Args.CancellationToken);
diff --git a/Octokit.Tests/Http/JsonHttpPipelineTests.cs b/Octokit.Tests/Http/JsonHttpPipelineTests.cs
index 874cb4e3..d533f041 100644
--- a/Octokit.Tests/Http/JsonHttpPipelineTests.cs
+++ b/Octokit.Tests/Http/JsonHttpPipelineTests.cs
@@ -30,7 +30,7 @@ namespace Octokit.Tests.Http
                 jsonPipeline.SerializeRequest(request);
 
                 Assert.Contains("Accept", request.Headers.Keys);
-                Assert.Equal("application/vnd.github.quicksilver-preview+json; charset=utf-8, application/vnd.github.v3+json; charset=utf-8", request.Headers["Accept"]);
+                Assert.Equal("application/vnd.github.v3+json", request.Headers["Accept"]);
             }
 
             [Fact]
diff --git a/Octokit.Tests/Reactive/ObservableIssuesLabelsClientTests.cs b/Octokit.Tests/Reactive/ObservableIssuesLabelsClientTests.cs
index 04f0988a..c075028d 100644
--- a/Octokit.Tests/Reactive/ObservableIssuesLabelsClientTests.cs
+++ b/Octokit.Tests/Reactive/ObservableIssuesLabelsClientTests.cs
@@ -30,7 +30,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForIssue("fake", "repo", 42);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), Args.EmptyDictionary, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), Args.EmptyDictionary, null);
             }
 
             [Fact]
@@ -42,7 +42,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForIssue(1, 42);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Args.EmptyDictionary, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Args.EmptyDictionary, null);
             }
 
             [Fact]
@@ -61,7 +61,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForIssue("fake", "repo", 42, options);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), null);
             }
 
             [Fact]
@@ -80,7 +80,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForIssue(1, 42, options);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), null);
             }
 
             [Fact]
@@ -114,7 +114,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForRepository("fake", "repo");
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), Args.EmptyDictionary, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), Args.EmptyDictionary, null);
             }
 
             [Fact]
@@ -126,7 +126,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForRepository(1);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), Args.EmptyDictionary, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), Args.EmptyDictionary, null);
             }
 
             [Fact]
@@ -145,7 +145,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForRepository("fake", "repo", options);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), null);
             }
 
             [Fact]
@@ -164,7 +164,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForRepository(1, options);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), null);
             }
 
             [Fact]
@@ -198,7 +198,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForMilestone("fake", "repo", 42);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/milestones/42/labels"), Args.EmptyDictionary, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/milestones/42/labels"), Args.EmptyDictionary, null);
             }
 
             [Fact]
@@ -210,7 +210,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForMilestone(1, 42);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/milestones/42/labels"), Args.EmptyDictionary, "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/milestones/42/labels"), Args.EmptyDictionary, null);
             }
 
             [Fact]
@@ -229,7 +229,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForMilestone("fake", "repo", 42, options);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/milestones/42/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/milestones/42/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), null);
             }
 
             [Fact]
@@ -248,7 +248,7 @@ namespace Octokit.Tests.Reactive
 
                 client.GetAllForMilestone(1, 42, options);
 
-                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/milestones/42/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/milestones/42/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), null);
             }
 
             [Fact]
@@ -367,7 +367,7 @@ namespace Octokit.Tests.Reactive
 
                 client.RemoveFromIssue("fake", "repo", 42, "label");
 
-                connection.Received().Delete<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels/label"), Arg.Any<object>(), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Delete<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repos/fake/repo/issues/42/labels/label"), Arg.Any<object>());
             }
 
             [Fact]
@@ -379,7 +379,7 @@ namespace Octokit.Tests.Reactive
 
                 client.RemoveFromIssue(1, 42, "label");
 
-                connection.Received().Delete<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels/label"), Arg.Any<object>(), "application/vnd.github.symmetra-preview+json");
+                connection.Received().Delete<IReadOnlyList<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels/label"), Arg.Any<object>());
             }
 
             [Fact]
diff --git a/Octokit.Tests/Reactive/ObservableRepoCollaboratorsClientTests.cs b/Octokit.Tests/Reactive/ObservableRepoCollaboratorsClientTests.cs
index 9eceeadc..8b0b78f8 100644
--- a/Octokit.Tests/Reactive/ObservableRepoCollaboratorsClientTests.cs
+++ b/Octokit.Tests/Reactive/ObservableRepoCollaboratorsClientTests.cs
@@ -70,7 +70,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(dictionary => dictionary.Count == 1),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
             }
 
             [Fact]
@@ -82,7 +82,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(dictionary => dictionary.Count == 1),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
             }
 
             [Fact]
@@ -102,7 +102,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(dictionary => dictionary.Count == 3),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
 
                 // StartPage is setted => only 1 option (StartPage) in dictionary
                 options = new ApiOptions
@@ -114,7 +114,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(dictionary => dictionary.Count == 2),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
 
                 // PageCount is setted => none of options in dictionary
                 options = new ApiOptions
@@ -126,7 +126,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(dictionary => dictionary.Count == 1),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
             }
 
             [Fact]
@@ -140,7 +140,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(d => d["affiliation"] == "all"),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
 
                 request = new RepositoryCollaboratorListRequest
                 {
@@ -151,7 +151,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(d => d["affiliation"] == "direct"),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
 
                 // PageCount is setted => none of options in dictionary
                 request = new RepositoryCollaboratorListRequest
@@ -163,7 +163,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(d => d["affiliation"] == "outside"),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
             }
 
             [Fact]
@@ -183,7 +183,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(dictionary => dictionary.Count == 3),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
 
                 // StartPage is setted => only 1 option (StartPage) in dictionary
                 options = new ApiOptions
@@ -195,7 +195,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(dictionary => dictionary.Count == 2),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
 
                 // PageCount is setted => none of options in dictionary
                 options = new ApiOptions
@@ -207,7 +207,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(dictionary => dictionary.Count == 1),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
             }
 
             [Fact]
@@ -221,7 +221,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(d => d["affiliation"] == "all"),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
 
                 request = new RepositoryCollaboratorListRequest
                 {
@@ -232,7 +232,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(d => d["affiliation"] == "direct"),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
 
                 request = new RepositoryCollaboratorListRequest
                 {
@@ -243,7 +243,7 @@ namespace Octokit.Tests.Reactive
                 _githubClient.Connection.Received(1)
                     .Get<List<User>>(Arg.Is<Uri>(u => u.ToString() == expectedUrl),
                         Arg.Is<IDictionary<string, string>>(d => d["affiliation"] == "outside"),
-                        "application/vnd.github.hellcat-preview+json");
+                        null);
             }
         }
 
@@ -650,4 +650,4 @@ namespace Octokit.Tests.Reactive
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Octokit.Tests/Reactive/ObservableRepositoriesClientTests.cs b/Octokit.Tests/Reactive/ObservableRepositoriesClientTests.cs
index 60b42ce2..43251edd 100644
--- a/Octokit.Tests/Reactive/ObservableRepositoriesClientTests.cs
+++ b/Octokit.Tests/Reactive/ObservableRepositoriesClientTests.cs
@@ -258,9 +258,9 @@ namespace Octokit.Tests.Reactive
                 var results = await repositoriesClient.GetAllForCurrent().ToArray();
 
                 Assert.Equal(7, results.Length);
-                gitHubClient.Connection.Received(1).Get<List<Repository>>(firstPageUrl, Arg.Any<IDictionary<string, string>>(), "application/vnd.github.drax-preview+json");
-                gitHubClient.Connection.Received(1).Get<List<Repository>>(secondPageUrl, Arg.Any<IDictionary<string, string>>(), "application/vnd.github.drax-preview+json");
-                gitHubClient.Connection.Received(1).Get<List<Repository>>(thirdPageUrl, Arg.Any<IDictionary<string, string>>(), "application/vnd.github.drax-preview+json");
+                gitHubClient.Connection.Received(1).Get<List<Repository>>(firstPageUrl, Arg.Any<IDictionary<string, string>>(), Args.AnyAcceptHeaders);
+                gitHubClient.Connection.Received(1).Get<List<Repository>>(secondPageUrl, Arg.Any<IDictionary<string, string>>(), Args.AnyAcceptHeaders);
+                gitHubClient.Connection.Received(1).Get<List<Repository>>(thirdPageUrl, Arg.Any<IDictionary<string, string>>(), Args.AnyAcceptHeaders);
             }
 
             [Fact(Skip = "See https://github.com/octokit/octokit.net/issues/1011 for issue to investigate this further")]
@@ -379,9 +379,9 @@ namespace Octokit.Tests.Reactive
                 var results = await repositoriesClient.GetAllPublic(new PublicRepositoryRequest(364L)).ToArray();
 
                 Assert.Equal(7, results.Length);
-                gitHubClient.Connection.Received(1).Get<List<Repository>>(firstPageUrl, null, "application/vnd.github.drax-preview+json");
-                gitHubClient.Connection.Received(1).Get<List<Repository>>(secondPageUrl, null, "application/vnd.github.drax-preview+json");
-                gitHubClient.Connection.Received(1).Get<List<Repository>>(thirdPageUrl, null, "application/vnd.github.drax-preview+json");
+                gitHubClient.Connection.Received(1).Get<List<Repository>>(firstPageUrl, Arg.Any<IDictionary<string, string>>(), Args.AnyAcceptHeaders);
+                gitHubClient.Connection.Received(1).Get<List<Repository>>(secondPageUrl, Arg.Any<IDictionary<string, string>>(), Args.AnyAcceptHeaders);
+                gitHubClient.Connection.Received(1).Get<List<Repository>>(thirdPageUrl, Arg.Any<IDictionary<string, string>>(), Args.AnyAcceptHeaders);
             }
         }
 
diff --git a/Octokit.Tests/Reactive/ObservableTeamsClientTests.cs b/Octokit.Tests/Reactive/ObservableTeamsClientTests.cs
index 66d29643..716c931b 100644
--- a/Octokit.Tests/Reactive/ObservableTeamsClientTests.cs
+++ b/Octokit.Tests/Reactive/ObservableTeamsClientTests.cs
@@ -83,8 +83,8 @@ namespace Octokit.Tests.Reactive
 
                 github.Connection.Received().Get<List<User>>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1/members"),
-                    Args.EmptyDictionary,
-                    "application/vnd.github.hellcat-preview+json");
+                    Arg.Any<Dictionary<string, string>>(),
+                    null);
             }
 
             [Fact]
@@ -98,7 +98,7 @@ namespace Octokit.Tests.Reactive
                 github.Connection.Received().Get<List<User>>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1/members"),
                     Arg.Is<Dictionary<string, string>>(d => d["role"] == "maintainer"),
-                    "application/vnd.github.hellcat-preview+json");
+                    null);
             }
 
             [Fact]
@@ -165,7 +165,7 @@ namespace Octokit.Tests.Reactive
                 gitHub.Connection.Received().Get<List<Team>>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1/teams"),
                     Args.EmptyDictionary,
-                    "application/vnd.github.hellcat-preview+json");
+                    null);
             }
 
             [Fact]
@@ -184,7 +184,7 @@ namespace Octokit.Tests.Reactive
                 gitHub.Connection.Received().Get<List<Team>>(
                     Arg.Is<Uri>(u => u.ToString() == "teams/1/teams"),
                     Arg.Is<IDictionary<string, string>>(dictionary => dictionary.Count == 2),
-                    "application/vnd.github.hellcat-preview+json");
+                    null);
             }
         }
 
@@ -232,4 +232,4 @@ namespace Octokit.Tests.Reactive
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Octokit/Clients/CommitsClient.cs b/Octokit/Clients/CommitsClient.cs
index f1278174..95bb25c1 100644
--- a/Octokit/Clients/CommitsClient.cs
+++ b/Octokit/Clients/CommitsClient.cs
@@ -35,7 +35,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(reference, nameof(reference));
 
-            return ApiConnection.Get<Commit>(ApiUrls.Commit(owner, name, reference), null, AcceptHeaders.SignatureVerificationPreview);
+            return ApiConnection.Get<Commit>(ApiUrls.Commit(owner, name, reference));
         }
 
         /// <summary>
diff --git a/Octokit/Clients/IssuesClient.cs b/Octokit/Clients/IssuesClient.cs
index 14b38e7c..c558f22d 100644
--- a/Octokit/Clients/IssuesClient.cs
+++ b/Octokit/Clients/IssuesClient.cs
@@ -513,7 +513,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(owner, nameof(owner));
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
 
-            return ApiConnection.Put<Issue>(ApiUrls.IssueLock(owner, name, number), new object(), null, AcceptHeaders.IssueLockingUnlockingApiPreview);
+            return ApiConnection.Put<Issue>(ApiUrls.IssueLock(owner, name, number), new object());
         }
 
         /// <summary>
@@ -525,7 +525,7 @@ namespace Octokit
         [ManualRoute("PUT", "/repositories/{id}/issues/{number}/lock")]
         public Task Lock(long repositoryId, int number)
         {
-            return ApiConnection.Put<Issue>(ApiUrls.IssueLock(repositoryId, number), new object(), null, AcceptHeaders.IssueLockingUnlockingApiPreview);
+            return ApiConnection.Put<Issue>(ApiUrls.IssueLock(repositoryId, number), new object());
         }
 
         /// <summary>
@@ -541,7 +541,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(owner, nameof(owner));
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
 
-            return ApiConnection.Delete(ApiUrls.IssueLock(owner, name, number), new object(), AcceptHeaders.IssueLockingUnlockingApiPreview);
+            return ApiConnection.Delete(ApiUrls.IssueLock(owner, name, number));
         }
 
         /// <summary>
@@ -553,7 +553,7 @@ namespace Octokit
         [ManualRoute("DELETE", "/repositories/{id}/issues/{number}/lock")]
         public Task Unlock(long repositoryId, int number)
         {
-            return ApiConnection.Delete(ApiUrls.IssueLock(repositoryId, number), new object(), AcceptHeaders.IssueLockingUnlockingApiPreview);
+            return ApiConnection.Delete(ApiUrls.IssueLock(repositoryId, number));
         }
     }
 }
diff --git a/Octokit/Clients/IssuesLabelsClient.cs b/Octokit/Clients/IssuesLabelsClient.cs
index f7aacba8..7527eb80 100644
--- a/Octokit/Clients/IssuesLabelsClient.cs
+++ b/Octokit/Clients/IssuesLabelsClient.cs
@@ -65,7 +65,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Label>(ApiUrls.IssueLabels(owner, name, number), null, AcceptHeaders.LabelsApiPreview, options);
+            return ApiConnection.GetAll<Label>(ApiUrls.IssueLabels(owner, name, number), options);
         }
 
         /// <summary>
@@ -82,7 +82,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Label>(ApiUrls.IssueLabels(repositoryId, number), null, AcceptHeaders.LabelsApiPreview, options);
+            return ApiConnection.GetAll<Label>(ApiUrls.IssueLabels(repositoryId, number), options);
         }
 
         /// <summary>
@@ -131,7 +131,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Label>(ApiUrls.Labels(owner, name), null, AcceptHeaders.LabelsApiPreview, options);
+            return ApiConnection.GetAll<Label>(ApiUrls.Labels(owner, name), options);
         }
 
         /// <summary>
@@ -147,7 +147,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Label>(ApiUrls.Labels(repositoryId), null, AcceptHeaders.LabelsApiPreview, options);
+            return ApiConnection.GetAll<Label>(ApiUrls.Labels(repositoryId), options);
         }
 
         /// <summary>
@@ -199,7 +199,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Label>(ApiUrls.MilestoneLabels(owner, name, number), null, AcceptHeaders.LabelsApiPreview, options);
+            return ApiConnection.GetAll<Label>(ApiUrls.MilestoneLabels(owner, name, number), options);
         }
 
         /// <summary>
@@ -216,7 +216,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Label>(ApiUrls.MilestoneLabels(repositoryId, number), null, AcceptHeaders.LabelsApiPreview, options);
+            return ApiConnection.GetAll<Label>(ApiUrls.MilestoneLabels(repositoryId, number), options);
         }
 
         /// <summary>
@@ -235,7 +235,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(labelName, nameof(labelName));
 
-            return ApiConnection.Get<Label>(ApiUrls.Label(owner, name, labelName), null, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Get<Label>(ApiUrls.Label(owner, name, labelName));
         }
 
         /// <summary>
@@ -251,7 +251,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(labelName, nameof(labelName));
 
-            return ApiConnection.Get<Label>(ApiUrls.Label(repositoryId, labelName), null, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Get<Label>(ApiUrls.Label(repositoryId, labelName));
         }
 
         /// <summary>
@@ -305,7 +305,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(newLabel, nameof(newLabel));
 
-            return ApiConnection.Post<Label>(ApiUrls.Labels(owner, name), newLabel, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Post<Label>(ApiUrls.Labels(owner, name), newLabel);
         }
 
         /// <summary>
@@ -321,7 +321,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(newLabel, nameof(newLabel));
 
-            return ApiConnection.Post<Label>(ApiUrls.Labels(repositoryId), newLabel, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Post<Label>(ApiUrls.Labels(repositoryId), newLabel);
         }
 
         /// <summary>
@@ -344,7 +344,7 @@ namespace Octokit
 
             // BUG: this should be a PATCH instead of POST
 
-            return ApiConnection.Post<Label>(ApiUrls.Label(owner, name, labelName), labelUpdate, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Post<Label>(ApiUrls.Label(owner, name, labelName), labelUpdate);
         }
 
         /// <summary>
@@ -364,7 +364,7 @@ namespace Octokit
 
             // BUG: this should be a PATCH instead of POST
 
-            return ApiConnection.Post<Label>(ApiUrls.Label(repositoryId, labelName), labelUpdate, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Post<Label>(ApiUrls.Label(repositoryId, labelName), labelUpdate);
         }
 
         /// <summary>
@@ -384,7 +384,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(labels, nameof(labels));
 
-            return ApiConnection.Post<IReadOnlyList<Label>>(ApiUrls.IssueLabels(owner, name, number), labels, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Post<IReadOnlyList<Label>>(ApiUrls.IssueLabels(owner, name, number), labels);
         }
 
         /// <summary>
@@ -401,7 +401,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(labels, nameof(labels));
 
-            return ApiConnection.Post<IReadOnlyList<Label>>(ApiUrls.IssueLabels(repositoryId, number), labels, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Post<IReadOnlyList<Label>>(ApiUrls.IssueLabels(repositoryId, number), labels);
         }
 
         /// <summary>
@@ -421,7 +421,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(labelName, nameof(labelName));
 
-            return ApiConnection.Delete<IReadOnlyList<Label>>(ApiUrls.IssueLabel(owner, name, number, labelName), AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Delete<IReadOnlyList<Label>>(ApiUrls.IssueLabel(owner, name, number, labelName), new object());
         }
 
         /// <summary>
@@ -438,7 +438,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(labelName, nameof(labelName));
 
-            return ApiConnection.Delete<IReadOnlyList<Label>>(ApiUrls.IssueLabel(repositoryId, number, labelName), AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Delete<IReadOnlyList<Label>>(ApiUrls.IssueLabel(repositoryId, number, labelName), new object());
         }
 
         /// <summary>
@@ -458,7 +458,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(labels, nameof(labels));
 
-            return ApiConnection.Put<IReadOnlyList<Label>>(ApiUrls.IssueLabels(owner, name, number), labels, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Put<IReadOnlyList<Label>>(ApiUrls.IssueLabels(owner, name, number), labels);
         }
 
         /// <summary>
@@ -475,7 +475,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(labels, nameof(labels));
 
-            return ApiConnection.Put<IReadOnlyList<Label>>(ApiUrls.IssueLabels(repositoryId, number), labels, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Put<IReadOnlyList<Label>>(ApiUrls.IssueLabels(repositoryId, number), labels);
         }
 
         /// <summary>
diff --git a/Octokit/Clients/MiscellaneousClient.cs b/Octokit/Clients/MiscellaneousClient.cs
index ddda6186..7ec2761e 100644
--- a/Octokit/Clients/MiscellaneousClient.cs
+++ b/Octokit/Clients/MiscellaneousClient.cs
@@ -102,7 +102,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(options, "options");
 
-            return ApiConnection.GetAll<LicenseMetadata>(ApiUrls.Licenses(), null, AcceptHeaders.LicensesApiPreview, options);
+            return ApiConnection.GetAll<LicenseMetadata>(ApiUrls.Licenses(), options);
         }
 
         /// <summary>
@@ -113,7 +113,7 @@ namespace Octokit
         [ManualRoute("GET", "/licenses/{key}")]
         public Task<License> GetLicense(string key)
         {
-            return ApiConnection.Get<License>(ApiUrls.Licenses(key), null, AcceptHeaders.LicensesApiPreview);
+            return ApiConnection.Get<License>(ApiUrls.Licenses(key));
         }
 
         /// <summary>
diff --git a/Octokit/Clients/PullRequestsClient.cs b/Octokit/Clients/PullRequestsClient.cs
index ecc4bb04..26cb6eef 100644
--- a/Octokit/Clients/PullRequestsClient.cs
+++ b/Octokit/Clients/PullRequestsClient.cs
@@ -295,7 +295,7 @@ namespace Octokit
             try
             {
                 var endpoint = ApiUrls.MergePullRequest(owner, name, number);
-                return await ApiConnection.Put<PullRequestMerge>(endpoint, mergePullRequest, null, AcceptHeaders.SquashCommitPreview).ConfigureAwait(false);
+                return await ApiConnection.Put<PullRequestMerge>(endpoint, mergePullRequest).ConfigureAwait(false);
             }
             catch (ApiException ex)
             {
@@ -328,7 +328,7 @@ namespace Octokit
             try
             {
                 var endpoint = ApiUrls.MergePullRequest(repositoryId, number);
-                return await ApiConnection.Put<PullRequestMerge>(endpoint, mergePullRequest, null, AcceptHeaders.SquashCommitPreview).ConfigureAwait(false);
+                return await ApiConnection.Put<PullRequestMerge>(endpoint, mergePullRequest).ConfigureAwait(false);
             }
             catch (ApiException ex)
             {
diff --git a/Octokit/Clients/RepoCollaboratorsClient.cs b/Octokit/Clients/RepoCollaboratorsClient.cs
index 993c6d61..d259a34b 100644
--- a/Octokit/Clients/RepoCollaboratorsClient.cs
+++ b/Octokit/Clients/RepoCollaboratorsClient.cs
@@ -145,7 +145,7 @@ namespace Octokit
             Ensure.ArgumentNotNull(request, nameof(request));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<User>(ApiUrls.RepoCollaborators(owner, name), request.ToParametersDictionary(), AcceptHeaders.NestedTeamsPreview, options);
+            return ApiConnection.GetAll<User>(ApiUrls.RepoCollaborators(owner, name), request.ToParametersDictionary(), options);
 
         }
 
@@ -165,7 +165,7 @@ namespace Octokit
             Ensure.ArgumentNotNull(request, nameof(request));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<User>(ApiUrls.RepoCollaborators(repositoryId), request.ToParametersDictionary(), AcceptHeaders.NestedTeamsPreview, options);
+            return ApiConnection.GetAll<User>(ApiUrls.RepoCollaborators(repositoryId), request.ToParametersDictionary(), options);
         }
 
         /// <summary>
@@ -370,7 +370,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(user, nameof(user));
 
 
-            return ApiConnection.Put<RepositoryInvitation>(ApiUrls.RepoCollaborator(owner, name, user), new object(), null, AcceptHeaders.InvitationsApiPreview);
+            return ApiConnection.Put<RepositoryInvitation>(ApiUrls.RepoCollaborator(owner, name, user), new object());
         }
 
         /// <summary>
@@ -392,7 +392,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(user, nameof(user));
             Ensure.ArgumentNotNull(permission, nameof(permission));
 
-            return ApiConnection.Put<RepositoryInvitation>(ApiUrls.RepoCollaborator(owner, name, user), permission, null, AcceptHeaders.InvitationsApiPreview);
+            return ApiConnection.Put<RepositoryInvitation>(ApiUrls.RepoCollaborator(owner, name, user), permission);
         }
 
         /// <summary>
@@ -409,7 +409,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(user, nameof(user));
 
-            return ApiConnection.Put<RepositoryInvitation>(ApiUrls.RepoCollaborator(repositoryId, user), new object(), null, AcceptHeaders.InvitationsApiPreview);
+            return ApiConnection.Put<RepositoryInvitation>(ApiUrls.RepoCollaborator(repositoryId, user), new object());
         }
 
         /// <summary>
@@ -428,7 +428,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(user, nameof(user));
             Ensure.ArgumentNotNull(permission, nameof(permission));
 
-            return ApiConnection.Put<RepositoryInvitation>(ApiUrls.RepoCollaborator(repositoryId, user), permission, null, AcceptHeaders.InvitationsApiPreview);
+            return ApiConnection.Put<RepositoryInvitation>(ApiUrls.RepoCollaborator(repositoryId, user), permission);
         }
 
         /// <summary>
diff --git a/Octokit/Clients/RepositoriesClient.cs b/Octokit/Clients/RepositoriesClient.cs
index 18dead09..b1ad8d7e 100644
--- a/Octokit/Clients/RepositoriesClient.cs
+++ b/Octokit/Clients/RepositoriesClient.cs
@@ -184,7 +184,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(repositoryTransfer, nameof(repositoryTransfer));
 
-            return ApiConnection.Post<Repository>(ApiUrls.RepositoryTransfer(owner, name), repositoryTransfer, AcceptHeaders.RepositoryTransferPreview);
+            return ApiConnection.Post<Repository>(ApiUrls.RepositoryTransfer(owner, name), repositoryTransfer);
         }
 
         /// <summary>
@@ -201,7 +201,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(repositoryTransfer, nameof(repositoryTransfer));
 
-            return ApiConnection.Post<Repository>(ApiUrls.RepositoryTransfer(repositoryId), repositoryTransfer, AcceptHeaders.RepositoryTransferPreview);
+            return ApiConnection.Post<Repository>(ApiUrls.RepositoryTransfer(repositoryId), repositoryTransfer);
         }
 
         /// <summary>
@@ -219,7 +219,7 @@ namespace Octokit
             Ensure.ArgumentNotNull(update, nameof(update));
             Ensure.ArgumentNotNull(update.Name, nameof(update.Name));
 
-            return ApiConnection.Patch<Repository>(ApiUrls.Repository(owner, name), update, AcceptHeaders.Concat(AcceptHeaders.SquashCommitPreview, AcceptHeaders.LicensesApiPreview));
+            return ApiConnection.Patch<Repository>(ApiUrls.Repository(owner, name), update);
         }
 
         /// <summary>
@@ -233,7 +233,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(update, nameof(update));
 
-            return ApiConnection.Patch<Repository>(ApiUrls.Repository(repositoryId), update, AcceptHeaders.Concat(AcceptHeaders.SquashCommitPreview, AcceptHeaders.LicensesApiPreview));
+            return ApiConnection.Patch<Repository>(ApiUrls.Repository(repositoryId), update);
         }
 
         /// <summary>
@@ -252,7 +252,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(owner, nameof(owner));
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
 
-            return ApiConnection.Get<Repository>(ApiUrls.Repository(owner, name), null, AcceptHeaders.Concat(AcceptHeaders.SquashCommitPreview, AcceptHeaders.LicensesApiPreview));
+            return ApiConnection.Get<Repository>(ApiUrls.Repository(owner, name));
         }
 
         /// <summary>
@@ -267,7 +267,7 @@ namespace Octokit
         [ManualRoute("GET", "/repositories/{id}")]
         public Task<Repository> Get(long repositoryId)
         {
-            return ApiConnection.Get<Repository>(ApiUrls.Repository(repositoryId), null, AcceptHeaders.Concat(AcceptHeaders.SquashCommitPreview, AcceptHeaders.LicensesApiPreview));
+            return ApiConnection.Get<Repository>(ApiUrls.Repository(repositoryId));
         }
 
         /// <summary>
@@ -283,7 +283,7 @@ namespace Octokit
         [ManualRoute("GET", "/repositories")]
         public Task<IReadOnlyList<Repository>> GetAllPublic()
         {
-            return ApiConnection.GetAll<Repository>(ApiUrls.AllPublicRepositories(), null, AcceptHeaders.LicensesApiPreview);
+            return ApiConnection.GetAll<Repository>(ApiUrls.AllPublicRepositories());
         }
 
         /// <summary>
@@ -304,7 +304,7 @@ namespace Octokit
 
             var url = ApiUrls.AllPublicRepositories(request.Since);
 
-            return ApiConnection.GetAll<Repository>(url, null, AcceptHeaders.LicensesApiPreview);
+            return ApiConnection.GetAll<Repository>(url);
         }
 
         /// <summary>
@@ -338,7 +338,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Repository>(ApiUrls.Repositories(), null, AcceptHeaders.LicensesApiPreview, options);
+            return ApiConnection.GetAll<Repository>(ApiUrls.Repositories(), options);
         }
 
         /// <summary>
@@ -378,7 +378,7 @@ namespace Octokit
             Ensure.ArgumentNotNull(request, nameof(request));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Repository>(ApiUrls.Repositories(), request.ToParametersDictionary(), AcceptHeaders.LicensesApiPreview, options);
+            return ApiConnection.GetAll<Repository>(ApiUrls.Repositories(), request.ToParametersDictionary(), options);
         }
 
         /// <summary>
@@ -415,7 +415,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(login, nameof(login));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Repository>(ApiUrls.Repositories(login), null, AcceptHeaders.LicensesApiPreview, options);
+            return ApiConnection.GetAll<Repository>(ApiUrls.Repositories(login), options);
         }
 
         /// <summary>
@@ -451,7 +451,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(organization, nameof(organization));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Repository>(ApiUrls.OrganizationRepositories(organization), null, AcceptHeaders.LicensesApiPreview, options);
+            return ApiConnection.GetAll<Repository>(ApiUrls.OrganizationRepositories(organization), options);
         }
 
         /// <summary>
@@ -808,7 +808,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Team>(ApiUrls.RepositoryTeams(owner, name), null, AcceptHeaders.NestedTeamsPreview, options);
+            return ApiConnection.GetAll<Team>(ApiUrls.RepositoryTeams(owner, name), options);
         }
 
         /// <summary>
@@ -912,7 +912,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(owner, nameof(owner));
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
 
-            return ApiConnection.Get<RepositoryContentLicense>(ApiUrls.RepositoryLicense(owner, name), null, AcceptHeaders.LicensesApiPreview);
+            return ApiConnection.Get<RepositoryContentLicense>(ApiUrls.RepositoryLicense(owner, name));
         }
 
         /// <summary>
@@ -926,7 +926,7 @@ namespace Octokit
         [ManualRoute("GET", "/repositories/{id}/license")]
         public Task<RepositoryContentLicense> GetLicenseContents(long repositoryId)
         {
-            return ApiConnection.Get<RepositoryContentLicense>(ApiUrls.RepositoryLicense(repositoryId), null, AcceptHeaders.LicensesApiPreview);
+            return ApiConnection.Get<RepositoryContentLicense>(ApiUrls.RepositoryLicense(repositoryId));
         }
 
         /// <summary>
diff --git a/Octokit/Clients/RepositoryBranchesClient.cs b/Octokit/Clients/RepositoryBranchesClient.cs
index e86211c9..f49825ff 100644
--- a/Octokit/Clients/RepositoryBranchesClient.cs
+++ b/Octokit/Clients/RepositoryBranchesClient.cs
@@ -13,8 +13,6 @@ namespace Octokit
     /// </remarks>
     public class RepositoryBranchesClient : ApiClient, IRepositoryBranchesClient
     {
-        private string protectedBranchesPreviewHeaders = AcceptHeaders.Concat(AcceptHeaders.ProtectedBranchesApiPreview, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
-
         /// <summary>
         /// Initializes a new GitHub Repository Branches API client.
         /// </summary>
@@ -72,7 +70,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Branch>(ApiUrls.RepoBranches(owner, name), null, protectedBranchesPreviewHeaders, options);
+            return ApiConnection.GetAll<Branch>(ApiUrls.RepoBranches(owner, name), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview, options);
         }
 
         /// <summary>
@@ -89,7 +87,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<Branch>(ApiUrls.RepoBranches(repositoryId), null, protectedBranchesPreviewHeaders, options);
+            return ApiConnection.GetAll<Branch>(ApiUrls.RepoBranches(repositoryId), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview, options);
         }
 
         /// <summary>
@@ -109,7 +107,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<Branch>(ApiUrls.RepoBranch(owner, name, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<Branch>(ApiUrls.RepoBranch(owner, name, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -126,7 +124,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<Branch>(ApiUrls.RepoBranch(repositoryId, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<Branch>(ApiUrls.RepoBranch(repositoryId, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -146,7 +144,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<BranchProtectionSettings>(ApiUrls.RepoBranchProtection(owner, name, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<BranchProtectionSettings>(ApiUrls.RepoBranchProtection(owner, name, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -163,7 +161,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<BranchProtectionSettings>(ApiUrls.RepoBranchProtection(repositoryId, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<BranchProtectionSettings>(ApiUrls.RepoBranchProtection(repositoryId, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -185,7 +183,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(update, nameof(update));
 
-            return ApiConnection.Put<BranchProtectionSettings>(ApiUrls.RepoBranchProtection(owner, name, branch), update, null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Put<BranchProtectionSettings>(ApiUrls.RepoBranchProtection(owner, name, branch), update, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -204,7 +202,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(update, nameof(update));
 
-            return ApiConnection.Put<BranchProtectionSettings>(ApiUrls.RepoBranchProtection(repositoryId, branch), update, null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Put<BranchProtectionSettings>(ApiUrls.RepoBranchProtection(repositoryId, branch), update, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -227,7 +225,7 @@ namespace Octokit
             var endpoint = ApiUrls.RepoBranchProtection(owner, name, branch);
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -253,7 +251,7 @@ namespace Octokit
             var endpoint = ApiUrls.RepoBranchProtection(repositoryId, branch);
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -279,7 +277,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<BranchProtectionRequiredStatusChecks>(ApiUrls.RepoRequiredStatusChecks(owner, name, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<BranchProtectionRequiredStatusChecks>(ApiUrls.RepoRequiredStatusChecks(owner, name, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -296,7 +294,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<BranchProtectionRequiredStatusChecks>(ApiUrls.RepoRequiredStatusChecks(repositoryId, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<BranchProtectionRequiredStatusChecks>(ApiUrls.RepoRequiredStatusChecks(repositoryId, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -318,7 +316,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(update, nameof(update));
 
-            return ApiConnection.Patch<BranchProtectionRequiredStatusChecks>(ApiUrls.RepoRequiredStatusChecks(owner, name, branch), update, protectedBranchesPreviewHeaders);
+            return ApiConnection.Patch<BranchProtectionRequiredStatusChecks>(ApiUrls.RepoRequiredStatusChecks(owner, name, branch), update, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -337,7 +335,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(update, nameof(update));
 
-            return ApiConnection.Patch<BranchProtectionRequiredStatusChecks>(ApiUrls.RepoRequiredStatusChecks(repositoryId, branch), update, protectedBranchesPreviewHeaders);
+            return ApiConnection.Patch<BranchProtectionRequiredStatusChecks>(ApiUrls.RepoRequiredStatusChecks(repositoryId, branch), update, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -361,7 +359,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -388,7 +386,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -414,7 +412,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(owner, name, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(owner, name, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -431,7 +429,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(repositoryId, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(repositoryId, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -453,7 +451,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(contexts, nameof(contexts));
 
-            return ApiConnection.Put<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(owner, name, branch), contexts, null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Put<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(owner, name, branch), contexts, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -472,7 +470,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(contexts, nameof(contexts));
 
-            return ApiConnection.Put<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(repositoryId, branch), contexts, null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Put<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(repositoryId, branch), contexts, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -494,7 +492,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(contexts, nameof(contexts));
 
-            return ApiConnection.Post<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(owner, name, branch), contexts, protectedBranchesPreviewHeaders);
+            return ApiConnection.Post<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(owner, name, branch), contexts, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -513,7 +511,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(contexts, nameof(contexts));
 
-            return ApiConnection.Post<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(repositoryId, branch), contexts, protectedBranchesPreviewHeaders);
+            return ApiConnection.Post<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(repositoryId, branch), contexts, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -535,7 +533,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(contexts, nameof(contexts));
 
-            return ApiConnection.Delete<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(owner, name, branch), contexts, protectedBranchesPreviewHeaders);
+            return ApiConnection.Delete<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(owner, name, branch), contexts, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -554,7 +552,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(contexts, nameof(contexts));
 
-            return ApiConnection.Delete<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(repositoryId, branch), contexts, protectedBranchesPreviewHeaders);
+            return ApiConnection.Delete<IReadOnlyList<string>>(ApiUrls.RepoRequiredStatusChecksContexts(repositoryId, branch), contexts, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -574,7 +572,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<BranchProtectionRequiredReviews>(ApiUrls.RepoProtectedBranchReviewEnforcement(owner, name, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<BranchProtectionRequiredReviews>(ApiUrls.RepoProtectedBranchReviewEnforcement(owner, name, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -591,7 +589,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<BranchProtectionRequiredReviews>(ApiUrls.RepoProtectedBranchReviewEnforcement(repositoryId, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<BranchProtectionRequiredReviews>(ApiUrls.RepoProtectedBranchReviewEnforcement(repositoryId, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -613,7 +611,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(update, nameof(update));
 
-            return ApiConnection.Patch<BranchProtectionRequiredReviews>(ApiUrls.RepoProtectedBranchReviewEnforcement(owner, name, branch), update, protectedBranchesPreviewHeaders);
+            return ApiConnection.Patch<BranchProtectionRequiredReviews>(ApiUrls.RepoProtectedBranchReviewEnforcement(owner, name, branch), update, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -632,7 +630,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(update, nameof(update));
 
-            return ApiConnection.Patch<BranchProtectionRequiredReviews>(ApiUrls.RepoProtectedBranchReviewEnforcement(repositoryId, branch), update, protectedBranchesPreviewHeaders);
+            return ApiConnection.Patch<BranchProtectionRequiredReviews>(ApiUrls.RepoProtectedBranchReviewEnforcement(repositoryId, branch), update, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -656,7 +654,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -683,7 +681,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -709,7 +707,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<EnforceAdmins>(ApiUrls.RepoProtectedBranchAdminEnforcement(owner, name, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<EnforceAdmins>(ApiUrls.RepoProtectedBranchAdminEnforcement(owner, name, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -726,7 +724,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<EnforceAdmins>(ApiUrls.RepoProtectedBranchAdminEnforcement(repositoryId, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<EnforceAdmins>(ApiUrls.RepoProtectedBranchAdminEnforcement(repositoryId, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -746,7 +744,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Post<EnforceAdmins>(ApiUrls.RepoProtectedBranchAdminEnforcement(owner, name, branch), new object(), protectedBranchesPreviewHeaders);
+            return ApiConnection.Post<EnforceAdmins>(ApiUrls.RepoProtectedBranchAdminEnforcement(owner, name, branch), new object(), AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -763,7 +761,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Post<EnforceAdmins>(ApiUrls.RepoProtectedBranchAdminEnforcement(repositoryId, branch), new object(), protectedBranchesPreviewHeaders);
+            return ApiConnection.Post<EnforceAdmins>(ApiUrls.RepoProtectedBranchAdminEnforcement(repositoryId, branch), new object(), AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -787,7 +785,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -814,7 +812,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -840,7 +838,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<BranchProtectionPushRestrictions>(ApiUrls.RepoRestrictions(owner, name, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<BranchProtectionPushRestrictions>(ApiUrls.RepoRestrictions(owner, name, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -857,7 +855,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<BranchProtectionPushRestrictions>(ApiUrls.RepoRestrictions(repositoryId, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<BranchProtectionPushRestrictions>(ApiUrls.RepoRestrictions(repositoryId, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -881,7 +879,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -908,7 +906,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, null, protectedBranchesPreviewHeaders).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -934,7 +932,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(owner, name, branch), null, AcceptHeaders.Concat(protectedBranchesPreviewHeaders, AcceptHeaders.NestedTeamsPreview));
+            return ApiConnection.Get<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(owner, name, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -951,7 +949,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(repositoryId, branch), null, AcceptHeaders.Concat(protectedBranchesPreviewHeaders, AcceptHeaders.NestedTeamsPreview));
+            return ApiConnection.Get<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(repositoryId, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -973,7 +971,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(teams, nameof(teams));
 
-            return ApiConnection.Put<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(owner, name, branch), teams, null, AcceptHeaders.Concat(protectedBranchesPreviewHeaders, AcceptHeaders.NestedTeamsPreview));
+            return ApiConnection.Put<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(owner, name, branch), teams, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -992,7 +990,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(teams, nameof(teams));
 
-            return ApiConnection.Put<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(repositoryId, branch), teams, null, AcceptHeaders.Concat(protectedBranchesPreviewHeaders, AcceptHeaders.NestedTeamsPreview));
+            return ApiConnection.Put<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(repositoryId, branch), teams, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1014,7 +1012,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(teams, nameof(teams));
 
-            return ApiConnection.Post<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(owner, name, branch), teams, AcceptHeaders.Concat(protectedBranchesPreviewHeaders, AcceptHeaders.NestedTeamsPreview));
+            return ApiConnection.Post<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(owner, name, branch), teams, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1033,7 +1031,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(teams, nameof(teams));
 
-            return ApiConnection.Post<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(repositoryId, branch), teams, AcceptHeaders.Concat(protectedBranchesPreviewHeaders, AcceptHeaders.NestedTeamsPreview));
+            return ApiConnection.Post<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(repositoryId, branch), teams, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1055,7 +1053,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(teams, nameof(teams));
 
-            return ApiConnection.Delete<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(owner, name, branch), teams, AcceptHeaders.Concat(protectedBranchesPreviewHeaders, AcceptHeaders.NestedTeamsPreview));
+            return ApiConnection.Delete<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(owner, name, branch), teams, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1074,7 +1072,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(teams, nameof(teams));
 
-            return ApiConnection.Delete<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(repositoryId, branch), teams, AcceptHeaders.Concat(protectedBranchesPreviewHeaders, AcceptHeaders.NestedTeamsPreview));
+            return ApiConnection.Delete<IReadOnlyList<Team>>(ApiUrls.RepoRestrictionsTeams(repositoryId, branch), teams, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1094,7 +1092,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(owner, name, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(owner, name, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1111,7 +1109,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
 
-            return ApiConnection.Get<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(repositoryId, branch), null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Get<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(repositoryId, branch), null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1133,7 +1131,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(users, nameof(users));
 
-            return ApiConnection.Put<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(owner, name, branch), users, null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Put<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(owner, name, branch), users, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1152,7 +1150,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(users, nameof(users));
 
-            return ApiConnection.Put<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(repositoryId, branch), users, null, protectedBranchesPreviewHeaders);
+            return ApiConnection.Put<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(repositoryId, branch), users, null, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1174,7 +1172,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(users, nameof(users));
 
-            return ApiConnection.Post<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(owner, name, branch), users, protectedBranchesPreviewHeaders);
+            return ApiConnection.Post<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(owner, name, branch), users, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1193,7 +1191,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(users, nameof(users));
 
-            return ApiConnection.Post<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(repositoryId, branch), users, protectedBranchesPreviewHeaders);
+            return ApiConnection.Post<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(repositoryId, branch), users, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1215,7 +1213,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(users, nameof(users));
 
-            return ApiConnection.Delete<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(owner, name, branch), users, protectedBranchesPreviewHeaders);
+            return ApiConnection.Delete<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(owner, name, branch), users, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
 
         /// <summary>
@@ -1234,7 +1232,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(branch, nameof(branch));
             Ensure.ArgumentNotNull(users, nameof(users));
 
-            return ApiConnection.Delete<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(repositoryId, branch), users, protectedBranchesPreviewHeaders);
+            return ApiConnection.Delete<IReadOnlyList<User>>(ApiUrls.RepoRestrictionsUsers(repositoryId, branch), users, AcceptHeaders.ProtectedBranchesRequiredApprovingApiPreview);
         }
     }
 }
diff --git a/Octokit/Clients/RepositoryInvitationsClient.cs b/Octokit/Clients/RepositoryInvitationsClient.cs
index 55b6a999..a0d495f4 100644
--- a/Octokit/Clients/RepositoryInvitationsClient.cs
+++ b/Octokit/Clients/RepositoryInvitationsClient.cs
@@ -17,7 +17,7 @@ namespace Octokit
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#accept-a-repository-invitation">API documentation</a> for more information.
-        /// </remarks>        
+        /// </remarks>
         /// <param name="invitationId">The id of the invitation</param>
         /// <exception cref="ApiException">Thrown when a general API error occurs.</exception>
         [ManualRoute("PATCH", "/user/repository_invitations/{invitation_id}")]
@@ -27,7 +27,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Patch(endpoint, AcceptHeaders.InvitationsApiPreview).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Patch(endpoint).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -41,7 +41,7 @@ namespace Octokit
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#decline-a-repository-invitation">API documentation</a> for more information.
-        /// </remarks>        
+        /// </remarks>
         /// <param name="invitationId">The id of the invitation</param>
         /// <exception cref="ApiException">Thrown when a general API error occurs.</exception>
         [ManualRoute("DELETE", "/user/repository_invitations/{invitation_id}")]
@@ -51,7 +51,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, new object(), AcceptHeaders.InvitationsApiPreview).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -76,7 +76,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await Connection.Delete(endpoint, new object(), AcceptHeaders.InvitationsApiPreview).ConfigureAwait(false);
+                var httpStatusCode = await Connection.Delete(endpoint).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -90,7 +90,7 @@ namespace Octokit
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#list-a-users-repository-invitations">API documentation</a> for more information.
-        /// </remarks>        
+        /// </remarks>
         /// <exception cref="ApiException">Thrown when a general API error occurs.</exception>
         [ManualRoute("GET", "/user/repository_invitations")]
         public Task<IReadOnlyList<RepositoryInvitation>> GetAllForCurrent()
@@ -110,7 +110,7 @@ namespace Octokit
         public Task<IReadOnlyList<RepositoryInvitation>> GetAllForCurrent(ApiOptions options)
         {
             Ensure.ArgumentNotNull(options, nameof(options));
-            return ApiConnection.GetAll<RepositoryInvitation>(ApiUrls.UserInvitations(), null, AcceptHeaders.InvitationsApiPreview, options);
+            return ApiConnection.GetAll<RepositoryInvitation>(ApiUrls.UserInvitations(), options);
         }
 
         /// <summary>
@@ -118,7 +118,7 @@ namespace Octokit
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#list-invitations-for-a-repository">API documentation</a> for more information.
-        /// </remarks>        
+        /// </remarks>
         /// <param name="repositoryId">The id of the repository</param>
         /// <exception cref="ApiException">Thrown when a general API error occurs.</exception>
         [ManualRoute("GET", "/repositories/{id}/invitations")]
@@ -132,7 +132,7 @@ namespace Octokit
         /// </summary>
         /// <remarks>
         /// See the <a href="https://developer.github.com/v3/repos/invitations/#list-invitations-for-a-repository">API documentation</a> for more information.
-        /// </remarks>        
+        /// </remarks>
         /// <param name="repositoryId">The id of the repository</param>
         /// <param name="options">Options for changing the API response</param>
         /// <exception cref="ApiException">Thrown when a general API error occurs.</exception>
@@ -140,7 +140,7 @@ namespace Octokit
         public Task<IReadOnlyList<RepositoryInvitation>> GetAllForRepository(long repositoryId, ApiOptions options)
         {
             Ensure.ArgumentNotNull(options, nameof(options));
-            return ApiConnection.GetAll<RepositoryInvitation>(ApiUrls.RepositoryInvitations(repositoryId), null, AcceptHeaders.InvitationsApiPreview, options);
+            return ApiConnection.GetAll<RepositoryInvitation>(ApiUrls.RepositoryInvitations(repositoryId), options);
         }
 
         /// <summary>
@@ -158,7 +158,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(permissions, nameof(permissions));
 
-            return ApiConnection.Patch<RepositoryInvitation>(ApiUrls.RepositoryInvitations(repositoryId, invitationId), permissions, AcceptHeaders.InvitationsApiPreview);
+            return ApiConnection.Patch<RepositoryInvitation>(ApiUrls.RepositoryInvitations(repositoryId, invitationId), permissions);
         }
     }
 }
diff --git a/Octokit/Clients/RepositoryPagesClient.cs b/Octokit/Clients/RepositoryPagesClient.cs
index 21ee5a68..4ebdacb4 100644
--- a/Octokit/Clients/RepositoryPagesClient.cs
+++ b/Octokit/Clients/RepositoryPagesClient.cs
@@ -160,7 +160,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(owner, nameof(owner));
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
 
-            return ApiConnection.Post<PagesBuild>(ApiUrls.RepositoryPageBuilds(owner, name), AcceptHeaders.PagesApiPreview);
+            return ApiConnection.Post<PagesBuild>(ApiUrls.RepositoryPageBuilds(owner, name));
         }
 
         /// <summary>
@@ -173,7 +173,7 @@ namespace Octokit
         [ManualRoute("POST", "/repositories/{id}/pages/builds")]
         public Task<PagesBuild> RequestPageBuild(long repositoryId)
         {
-            return ApiConnection.Post<PagesBuild>(ApiUrls.RepositoryPageBuilds(repositoryId), AcceptHeaders.PagesApiPreview);
+            return ApiConnection.Post<PagesBuild>(ApiUrls.RepositoryPageBuilds(repositoryId));
         }
     }
 }
diff --git a/Octokit/Clients/RepositoryTrafficClient.cs b/Octokit/Clients/RepositoryTrafficClient.cs
index f5504d94..73bc4575 100644
--- a/Octokit/Clients/RepositoryTrafficClient.cs
+++ b/Octokit/Clients/RepositoryTrafficClient.cs
@@ -18,7 +18,7 @@ namespace Octokit
         [ManualRoute("GET", "/repositories/{id}/traffic/popular/paths")]
         public Task<IReadOnlyList<RepositoryTrafficPath>> GetAllPaths(long repositoryId)
         {
-            return ApiConnection.GetAll<RepositoryTrafficPath>(ApiUrls.RepositoryTrafficPaths(repositoryId), AcceptHeaders.RepositoryTrafficApiPreview);
+            return ApiConnection.GetAll<RepositoryTrafficPath>(ApiUrls.RepositoryTrafficPaths(repositoryId));
         }
 
         /// <summary>
@@ -33,7 +33,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(owner, nameof(owner));
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
 
-            return ApiConnection.GetAll<RepositoryTrafficPath>(ApiUrls.RepositoryTrafficPaths(owner, name), AcceptHeaders.RepositoryTrafficApiPreview);
+            return ApiConnection.GetAll<RepositoryTrafficPath>(ApiUrls.RepositoryTrafficPaths(owner, name));
         }
 
         /// <summary>
@@ -44,7 +44,7 @@ namespace Octokit
         [ManualRoute("GET", "/repositories/{id}/traffic/popular/referrers")]
         public Task<IReadOnlyList<RepositoryTrafficReferrer>> GetAllReferrers(long repositoryId)
         {
-            return ApiConnection.GetAll<RepositoryTrafficReferrer>(ApiUrls.RepositoryTrafficReferrers(repositoryId), AcceptHeaders.RepositoryTrafficApiPreview);
+            return ApiConnection.GetAll<RepositoryTrafficReferrer>(ApiUrls.RepositoryTrafficReferrers(repositoryId));
         }
 
         /// <summary>
@@ -59,7 +59,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(owner, nameof(owner));
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
 
-            return ApiConnection.GetAll<RepositoryTrafficReferrer>(ApiUrls.RepositoryTrafficReferrers(owner, name), AcceptHeaders.RepositoryTrafficApiPreview);
+            return ApiConnection.GetAll<RepositoryTrafficReferrer>(ApiUrls.RepositoryTrafficReferrers(owner, name));
         }
 
         /// <summary>
@@ -73,7 +73,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(per, nameof(per));
 
-            return ApiConnection.Get<RepositoryTrafficCloneSummary>(ApiUrls.RepositoryTrafficClones(repositoryId), per.ToParametersDictionary(), AcceptHeaders.RepositoryTrafficApiPreview);
+            return ApiConnection.Get<RepositoryTrafficCloneSummary>(ApiUrls.RepositoryTrafficClones(repositoryId), per.ToParametersDictionary());
         }
 
         /// <summary>
@@ -90,7 +90,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(per, nameof(per));
 
-            return ApiConnection.Get<RepositoryTrafficCloneSummary>(ApiUrls.RepositoryTrafficClones(owner, name), per.ToParametersDictionary(), AcceptHeaders.RepositoryTrafficApiPreview);
+            return ApiConnection.Get<RepositoryTrafficCloneSummary>(ApiUrls.RepositoryTrafficClones(owner, name), per.ToParametersDictionary());
         }
 
         /// <summary>
@@ -104,7 +104,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(per, nameof(per));
 
-            return ApiConnection.Get<RepositoryTrafficViewSummary>(ApiUrls.RepositoryTrafficViews(repositoryId), per.ToParametersDictionary(), AcceptHeaders.RepositoryTrafficApiPreview);
+            return ApiConnection.Get<RepositoryTrafficViewSummary>(ApiUrls.RepositoryTrafficViews(repositoryId), per.ToParametersDictionary());
         }
 
         /// <summary>
@@ -121,7 +121,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNull(per, nameof(per));
 
-            return ApiConnection.Get<RepositoryTrafficViewSummary>(ApiUrls.RepositoryTrafficViews(owner, name), per.ToParametersDictionary(), AcceptHeaders.RepositoryTrafficApiPreview);
+            return ApiConnection.Get<RepositoryTrafficViewSummary>(ApiUrls.RepositoryTrafficViews(owner, name), per.ToParametersDictionary());
         }
     }
 }
diff --git a/Octokit/Clients/SearchClient.cs b/Octokit/Clients/SearchClient.cs
index 9c1056bd..f1b86c35 100644
--- a/Octokit/Clients/SearchClient.cs
+++ b/Octokit/Clients/SearchClient.cs
@@ -81,7 +81,7 @@ namespace Octokit
         public Task<SearchLabelsResult> SearchLabels(SearchLabelsRequest search)
         {
             Ensure.ArgumentNotNull(search, nameof(search));
-            return ApiConnection.Get<SearchLabelsResult>(ApiUrls.SearchLabels(), search.Parameters, AcceptHeaders.LabelsApiPreview);
+            return ApiConnection.Get<SearchLabelsResult>(ApiUrls.SearchLabels(), search.Parameters);
         }
     }
 }
diff --git a/Octokit/Clients/TagsClient.cs b/Octokit/Clients/TagsClient.cs
index bf6f5298..caf856b5 100644
--- a/Octokit/Clients/TagsClient.cs
+++ b/Octokit/Clients/TagsClient.cs
@@ -35,7 +35,7 @@ namespace Octokit
             Ensure.ArgumentNotNullOrEmptyString(name, nameof(name));
             Ensure.ArgumentNotNullOrEmptyString(reference, nameof(reference));
 
-            return ApiConnection.Get<GitTag>(ApiUrls.Tag(owner, name, reference), null, AcceptHeaders.SignatureVerificationPreview);
+            return ApiConnection.Get<GitTag>(ApiUrls.Tag(owner, name, reference));
         }
 
         /// <summary>
@@ -51,7 +51,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNullOrEmptyString(reference, nameof(reference));
 
-            return ApiConnection.Get<GitTag>(ApiUrls.Tag(repositoryId, reference), null, AcceptHeaders.SignatureVerificationPreview);
+            return ApiConnection.Get<GitTag>(ApiUrls.Tag(repositoryId, reference));
         }
 
         /// <summary>
diff --git a/Octokit/Clients/TeamsClient.cs b/Octokit/Clients/TeamsClient.cs
index 4e0c5b66..1a98aab4 100644
--- a/Octokit/Clients/TeamsClient.cs
+++ b/Octokit/Clients/TeamsClient.cs
@@ -35,7 +35,7 @@ namespace Octokit
         {
             var endpoint = ApiUrls.Teams(id);
 
-            return ApiConnection.Get<Team>(endpoint, null, AcceptHeaders.NestedTeamsPreview);
+            return ApiConnection.Get<Team>(endpoint);
         }
 
         /// <summary>
@@ -64,7 +64,7 @@ namespace Octokit
             Ensure.ArgumentNotNull(options, nameof(options));
 
             var endpoint = ApiUrls.OrganizationTeams(org);
-            return ApiConnection.GetAll<Team>(endpoint, null, AcceptHeaders.NestedTeamsPreview, options);
+            return ApiConnection.GetAll<Team>(endpoint, options);
         }
 
         /// <summary>
@@ -91,7 +91,7 @@ namespace Octokit
 
             var endpoint = ApiUrls.UserTeams();
 
-            return ApiConnection.GetAll<Team>(endpoint, null, AcceptHeaders.NestedTeamsPreview, options);
+            return ApiConnection.GetAll<Team>(endpoint, options);
         }
 
         /// <summary>
@@ -122,7 +122,7 @@ namespace Octokit
 
             var endpoint = ApiUrls.TeamChildTeams(id);
 
-            return ApiConnection.GetAll<Team>(endpoint, null, AcceptHeaders.NestedTeamsPreview, options);
+            return ApiConnection.GetAll<Team>(endpoint, options);
         }
 
         /// <summary>
@@ -153,7 +153,7 @@ namespace Octokit
 
             var endpoint = ApiUrls.TeamMembers(id);
 
-            return ApiConnection.GetAll<User>(endpoint, null, AcceptHeaders.NestedTeamsPreview, options);
+            return ApiConnection.GetAll<User>(endpoint, options);
         }
 
         /// <summary>
@@ -189,7 +189,7 @@ namespace Octokit
 
             var endpoint = ApiUrls.TeamMembers(id);
 
-            return ApiConnection.GetAll<User>(endpoint, request.ToParametersDictionary(), AcceptHeaders.NestedTeamsPreview, options);
+            return ApiConnection.GetAll<User>(endpoint, request.ToParametersDictionary(), options);
         }
 
         /// <summary>
@@ -209,7 +209,7 @@ namespace Octokit
 
             var endpoint = ApiUrls.TeamMember(id, login);
 
-            return ApiConnection.Get<TeamMembershipDetails>(endpoint, null, AcceptHeaders.NestedTeamsPreview);
+            return ApiConnection.Get<TeamMembershipDetails>(endpoint);
         }
 
         /// <summary>
@@ -224,7 +224,7 @@ namespace Octokit
             Ensure.ArgumentNotNull(team, nameof(team));
 
             var endpoint = ApiUrls.OrganizationTeams(org);
-            return ApiConnection.Post<Team>(endpoint, team, AcceptHeaders.NestedTeamsPreview);
+            return ApiConnection.Post<Team>(endpoint, team);
         }
 
         /// <summary>
@@ -238,7 +238,7 @@ namespace Octokit
             Ensure.ArgumentNotNull(team, nameof(team));
 
             var endpoint = ApiUrls.Teams(id);
-            return ApiConnection.Patch<Team>(endpoint, team, AcceptHeaders.NestedTeamsPreview);
+            return ApiConnection.Patch<Team>(endpoint, team);
         }
 
         /// <summary>
@@ -251,7 +251,7 @@ namespace Octokit
         {
             var endpoint = ApiUrls.Teams(id);
 
-            return ApiConnection.Delete(endpoint, new object(), AcceptHeaders.NestedTeamsPreview);
+            return ApiConnection.Delete(endpoint);
         }
 
         /// <summary>
@@ -292,7 +292,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await ApiConnection.Connection.Delete(endpoint, null, AcceptHeaders.NestedTeamsPreview).ConfigureAwait(false);
+                var httpStatusCode = await ApiConnection.Connection.Delete(endpoint).ConfigureAwait(false);
 
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
@@ -328,7 +328,7 @@ namespace Octokit
 
             var endpoint = ApiUrls.TeamRepositories(id);
 
-            return ApiConnection.GetAll<Repository>(endpoint, null, AcceptHeaders.NestedTeamsPreview, options);
+            return ApiConnection.GetAll<Repository>(endpoint, options);
         }
 
         /// <summary>
@@ -358,7 +358,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await ApiConnection.Connection.Put(endpoint, AcceptHeaders.NestedTeamsPreview).ConfigureAwait(false);
+                var httpStatusCode = await ApiConnection.Connection.Put(endpoint).ConfigureAwait(false);
                 return httpStatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -398,7 +398,7 @@ namespace Octokit
 
             try
             {
-                var httpStatusCode = await ApiConnection.Connection.Put<HttpStatusCode>(endpoint, permission, "", AcceptHeaders.NestedTeamsPreview).ConfigureAwait(false);
+                var httpStatusCode = await ApiConnection.Connection.Put<HttpStatusCode>(endpoint, permission).ConfigureAwait(false);
                 return httpStatusCode.HttpResponse.StatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
@@ -464,7 +464,7 @@ namespace Octokit
 
             try
             {
-                var response = await ApiConnection.Connection.Get<string>(endpoint, null, AcceptHeaders.NestedTeamsPreview).ConfigureAwait(false);
+                var response = await ApiConnection.Connection.Get<string>(endpoint, null, AcceptHeaders.StableVersionJson).ConfigureAwait(false);
                 return response.HttpResponse.StatusCode == HttpStatusCode.NoContent;
             }
             catch (NotFoundException)
diff --git a/Octokit/Clients/UserGpgKeysClient.cs b/Octokit/Clients/UserGpgKeysClient.cs
index 76146b5f..29ba1885 100644
--- a/Octokit/Clients/UserGpgKeysClient.cs
+++ b/Octokit/Clients/UserGpgKeysClient.cs
@@ -47,7 +47,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(options, nameof(options));
 
-            return ApiConnection.GetAll<GpgKey>(ApiUrls.GpgKeys(), null, AcceptHeaders.GpgKeysPreview, options);
+            return ApiConnection.GetAll<GpgKey>(ApiUrls.GpgKeys(), options);
         }
 
         /// <summary>
@@ -61,7 +61,7 @@ namespace Octokit
         [ManualRoute("GET", "/user/gpg_keys/{id}")]
         public Task<GpgKey> Get(int id)
         {
-            return ApiConnection.Get<GpgKey>(ApiUrls.GpgKeys(id), null, AcceptHeaders.GpgKeysPreview);
+            return ApiConnection.Get<GpgKey>(ApiUrls.GpgKeys(id));
         }
 
         /// <summary>
@@ -77,7 +77,7 @@ namespace Octokit
         {
             Ensure.ArgumentNotNull(newGpgKey, nameof(newGpgKey));
 
-            return ApiConnection.Post<GpgKey>(ApiUrls.GpgKeys(), newGpgKey, AcceptHeaders.GpgKeysPreview);
+            return ApiConnection.Post<GpgKey>(ApiUrls.GpgKeys(), newGpgKey);
         }
 
         /// <summary>
@@ -91,7 +91,7 @@ namespace Octokit
         [ManualRoute("DELETE", "/user/gpg_keys/{id}")]
         public Task Delete(int id)
         {
-            return ApiConnection.Delete(ApiUrls.GpgKeys(id), new object(), AcceptHeaders.GpgKeysPreview);
+            return ApiConnection.Delete(ApiUrls.GpgKeys(id));
         }
     }
 }
diff --git a/Octokit/Helpers/AcceptHeaders.cs b/Octokit/Helpers/AcceptHeaders.cs
index d7ab7953..6f869f6d 100644
--- a/Octokit/Helpers/AcceptHeaders.cs
+++ b/Octokit/Helpers/AcceptHeaders.cs
@@ -7,63 +7,33 @@ namespace Octokit
     {
         public const string StableVersion = "application/vnd.github.v3";
 
-        public const string StableVersionHtml = "application/vnd.github.html";
+        public const string StableVersionHtml = "application/vnd.github.v3.html";
 
-        public const string RedirectsPreviewThenStableVersionJson = "application/vnd.github.quicksilver-preview+json; charset=utf-8, application/vnd.github.v3+json; charset=utf-8";
+        public const string StableVersionJson = "application/vnd.github.v3+json";
 
         public const string CommitReferenceSha1MediaType = "application/vnd.github.v3.sha";
 
-        public const string OrganizationPermissionsPreview = "application/vnd.github.ironman-preview+json";
-
-        /// <summary>
-        /// Support for retrieving information about open source license usage on GitHub.com.
-        /// Custom media type: drax-preview Announced: 2015-03-09 Update 1: 2015-06-24 Update 2: 2015-08-04
-        /// </summary>
-        public const string LicensesApiPreview = "application/vnd.github.drax-preview+json";
-
-        public const string ProtectedBranchesApiPreview = "application/vnd.github.loki-preview+json";
-
         public const string StarCreationTimestamps = "application/vnd.github.v3.star+json";
 
-        public const string IssueLockingUnlockingApiPreview = "application/vnd.github.the-key-preview+json";
-
-        public const string SquashCommitPreview = "application/vnd.github.polaris-preview+json";
-
         public const string MigrationsApiPreview = "application/vnd.github.wyandotte-preview+json";
 
         public const string ReactionsPreview = "application/vnd.github.squirrel-girl-preview+json";
 
-        public const string SignatureVerificationPreview = "application/vnd.github.cryptographer-preview+sha";
-
-        [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Gpg")]
-        public const string GpgKeysPreview = "application/vnd.github.cryptographer-preview";
-
         public const string DeploymentApiPreview = "application/vnd.github.ant-man-preview+json";
 
-        public const string InvitationsApiPreview = "application/vnd.github.swamp-thing-preview+json";
-
-        public const string PagesApiPreview = "application/vnd.github.mister-fantastic-preview+json";
-
         public const string IssueTimelineApiPreview = "application/vnd.github.mockingbird-preview+json";
 
-        public const string RepositoryTrafficApiPreview = "application/vnd.github.spiderman-preview";
-
         public const string DraftPullRequestApiPreview = "application/vnd.github.shadow-cat-preview+json";
 
         public const string ProjectsApiPreview = "application/vnd.github.inertia-preview+json";
 
+        [Obsolete("API is considered legacy")]
         public const string OrganizationMembershipPreview = "application/vnd.github.korra-preview+json";
 
-        public const string NestedTeamsPreview = "application/vnd.github.hellcat-preview+json";
-
         public const string GitHubAppsPreview = "application/vnd.github.machine-man-preview+json";
 
         public const string PreReceiveEnvironmentsPreview = "application/vnd.github.eye-scream-preview+json";
 
-        public const string LabelsApiPreview = "application/vnd.github.symmetra-preview+json";
-
-        public const string RepositoryTransferPreview = "application/vnd.github.nightshade-preview+json";
-
         public const string ChecksApiPreview = "application/vnd.github.antiope-preview+json";
 
         public const string ProtectedBranchesRequiredApprovingApiPreview = "application/vnd.github.luke-cage-preview+json";
diff --git a/Octokit/Http/JsonHttpPipeline.cs b/Octokit/Http/JsonHttpPipeline.cs
index 80830a9a..7296cd37 100644
--- a/Octokit/Http/JsonHttpPipeline.cs
+++ b/Octokit/Http/JsonHttpPipeline.cs
@@ -30,7 +30,7 @@ namespace Octokit.Internal
 
             if (!request.Headers.ContainsKey("Accept"))
             {
-                request.Headers["Accept"] = AcceptHeaders.RedirectsPreviewThenStableVersionJson;
+                request.Headers["Accept"] = AcceptHeaders.StableVersionJson;
             }
 
             if (request.Method == HttpMethod.Get || request.Body == null) return;