9 files declare their use of GroupContentInterface in Group 8

GroupContentAccessControlHandler.php in src/Plugin/GroupContentAccessControlHandler.php

GroupContentAccessControlHandlerInterface.php in src/Plugin/GroupContentAccessControlHandlerInterface.php

GroupContentAccessControlHandlerTest.php in tests/src/Unit/GroupContentAccessControlHandlerTest.php

GroupContentEnablerBase.php in src/Plugin/GroupContentEnablerBase.php

GroupContentEnablerInterface.php in src/Plugin/GroupContentEnablerInterface.php

GroupContentEntityAccessControlHandlerTest.php in tests/src/Unit/GroupContentEntityAccessControlHandlerTest.php

GroupMembership.php in src/GroupMembership.php

GroupMembership.php in src/Plugin/GroupContentEnabler/GroupMembership.php

GroupOwnsContentAccessCheck.php in src/Access/GroupOwnsContentAccessCheck.php