8 files declare their use of ConfigEntityBundleBase in Drupal 8

BlockContentType.php in core/modules/block_content/src/Entity/BlockContentType.php

CommentType.php in core/modules/comment/src/Entity/CommentType.php

ContactForm.php in core/modules/contact/src/Entity/ContactForm.php

EntityTestBundle.php in core/modules/system/tests/modules/entity_test/src/Entity/EntityTestBundle.php

MediaType.php in core/modules/media/src/Entity/MediaType.php

NodeType.php in core/modules/node/src/Entity/NodeType.php

ShortcutSet.php in core/modules/shortcut/src/Entity/ShortcutSet.php

Vocabulary.php in core/modules/taxonomy/src/Entity/Vocabulary.php