10 classes are annotated with MediaSource in Drupal 9

AudioFile in core/modules/media/src/Plugin/media/Source/AudioFile.php

Media source wrapping around an audio file.

File in core/modules/media/src/Plugin/media/Source/File.php

File entity media source.

Image in core/modules/media/src/Plugin/media/Source/Image.php

Image entity media source.

OEmbed in core/modules/media/src/Plugin/media/Source/OEmbed.php

Provides a media source plugin for oEmbed resources.

Test in core/modules/media/tests/modules/media_test_source/src/Plugin/media/Source/Test.php

Provides test media source.

TestDifferentDisplays in core/modules/media/tests/modules/media_test_source/src/Plugin/media/Source/TestDifferentDisplays.php

Provides test media source.

TestTranslation in core/modules/media/tests/modules/media_test_source/src/Plugin/media/Source/TestTranslation.php

Provides test media source.

TestWithConstraints in core/modules/media/tests/modules/media_test_source/src/Plugin/media/Source/TestWithConstraints.php

Provides generic media type.

TestWithHiddenSourceField in core/modules/media/tests/modules/media_test_source/src/Plugin/media/Source/TestWithHiddenSourceField.php

Provides test media source.

VideoFile in core/modules/media/src/Plugin/media/Source/VideoFile.php

Media source wrapping around a video file.