2 model classes were missing one - technically not needed for these 2 classes due to their api calls being basic data types that then get populated into these objects, but it's easiest to just add them to these 2 classes so the test can pass on all response models
These methods actually returned mutable collections that happen
to implement the readonly interfaces. User could cast them to
the actual type and add things. I'd rather avoid even that
possibility by making these truly return readonly stuff.