28 files declare their use of ContentEntityInterface in Zircon Profile 8

BlockContentInterface.php in core/modules/block_content/src/BlockContentInterface.php

Contains \Drupal\block_content\BlockContentInterface.

CommentInterface.php in core/modules/comment/src/CommentInterface.php

Contains \Drupal\comment\CommentInterface.

ContentEntityBaseUnitTest.php in core/tests/Drupal/Tests/Core/Entity/ContentEntityBaseUnitTest.php

Contains \Drupal\Tests\Core\Entity\ContentEntityBaseUnitTest.

ContentTranslationController.php in core/modules/content_translation/src/Controller/ContentTranslationController.php

Contains \Drupal\content_translation\Controller\ContentTranslationController.

content_translation.module in core/modules/content_translation/content_translation.module

Allows entities to be translated into different languages.

entity.api.php in core/lib/Drupal/Core/Entity/entity.api.php

Hooks and documentation related to entities.

EntityContentBase.php in core/modules/migrate/src/Plugin/migrate/destination/EntityContentBase.php

Contains \Drupal\migrate\Plugin\migrate\destination\EntityContentBase.

EntityContentBaseTest.php in core/modules/migrate/tests/src/Unit/Plugin/migrate/destination/EntityContentBaseTest.php

Contains \Drupal\Tests\migrate\Unit\Plugin\migrate\destination\EntityContentBaseTest

EntityFieldManagerTest.php in core/tests/Drupal/Tests/Core/Entity/EntityFieldManagerTest.php

Contains \Drupal\Tests\Core\Entity\EntityFieldManagerTest.

EntityFileTest.php in core/modules/file/src/Tests/Migrate/EntityFileTest.php

Contains \Drupal\file\Tests\Migrate\EntityFileTest.

EntityRepositoryTest.php in core/tests/Drupal/Tests/Core/Entity/EntityRepositoryTest.php

Contains \Drupal\Tests\Core\Entity\EntityRepositoryTest.

EntityRevision.php in core/modules/migrate/src/Plugin/migrate/destination/EntityRevision.php

Contains \Drupal\migrate\Plugin\migrate\destination\EntityRevision.

EntityRevisionTest.php in core/modules/migrate/tests/src/Unit/destination/EntityRevisionTest.php

Contains \Drupal\Tests\migrate\Unit\destination\EntityRevisionTest.

FeedInterface.php in core/modules/aggregator/src/FeedInterface.php

Contains \Drupal\aggregator\FeedInterface.

FieldTranslationSynchronizer.php in core/modules/content_translation/src/FieldTranslationSynchronizer.php

Contains \Drupal\content_translation\FieldTranslationSynchronizer.

FieldTranslationSynchronizerInterface.php in core/modules/content_translation/src/FieldTranslationSynchronizerInterface.php

Contains \Drupal\content_translation\FieldTranslationSynchronizerInterface.

FileInterface.php in core/modules/file/src/FileInterface.php

Contains \Drupal\file\FileInterface.

ItemInterface.php in core/modules/aggregator/src/ItemInterface.php

Contains \Drupal\aggregator\ItemInterface.

KeyValueContentEntityStorage.php in core/lib/Drupal/Core/Entity/KeyValueStore/KeyValueContentEntityStorage.php

Contains \Drupal\Core\Entity\KeyValueStore\KeyValueContentEntityStorage.

LanguageNegotiationContentEntity.php in core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationContentEntity.php

Contains \Drupal\language\Plugin\LanguageNegotiation\LanguageNegotiationContentEntity.

MenuLinkContentInterface.php in core/modules/menu_link_content/src/MenuLinkContentInterface.php

Contains \Drupal\menu_link_content\MenuLinkContentInterface.

MessageInterface.php in core/modules/contact/src/MessageInterface.php

Contains \Drupal\contact\MessageInterface.

NodeInterface.php in core/modules/node/src/NodeInterface.php

Contains \Drupal\node\NodeInterface.

ShortcutInterface.php in core/modules/shortcut/src/ShortcutInterface.php

Contains \Drupal\shortcut\ShortcutInterface.

SqlContentEntityStorage.php in core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php

Contains \Drupal\Core\Entity\Sql\SqlContentEntityStorage.

TermInterface.php in core/modules/taxonomy/src/TermInterface.php

Contains \Drupal\taxonomy\TermInterface.

UserInterface.php in core/modules/user/src/UserInterface.php

Contains \Drupal\user\UserInterface.

UserStorage.php in core/modules/user/src/UserStorage.php

Contains \Drupal\user\UserStorage.