14 files declare their use of EntityNG

Comment.php in drupal/core/modules/comment/lib/Drupal/comment/Plugin/Core/Entity/Comment.php
Definition of Drupal\comment\Plugin\Core\Entity\Comment.
CustomBlock.php in drupal/core/modules/block/custom_block/lib/Drupal/custom_block/Plugin/Core/Entity/CustomBlock.php
Contains \Drupal\custom_block\Plugin\Core\Entity\CustomBlock.
EntityNormalizer.php in drupal/core/modules/hal/lib/Drupal/hal/Normalizer/EntityNormalizer.php
Contains \Drupal\hal\Normalizer\EntityNormalizer.
EntityTest.php in drupal/core/modules/system/tests/modules/entity_test/lib/Drupal/entity_test/Plugin/Core/Entity/EntityTest.php
Definition of Drupal\entity_test\Plugin\Core\Entity\EntityTest.
EntityTranslationUITest.php in drupal/core/modules/translation_entity/lib/Drupal/translation_entity/Tests/EntityTranslationUITest.php
Definition of Drupal\entity\Tests\EntityTranslationUITest.
Feed.php in drupal/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Core/Entity/Feed.php
Contains \Drupal\aggregator\Plugin\Core\Entity\Feed.
FieldTranslationSynchronizer.php in drupal/core/modules/translation_entity/lib/Drupal/translation_entity/FieldTranslationSynchronizer.php
Contains \Drupal\translation_entity\FieldTranslationSynchronizer.
Item.php in drupal/core/modules/aggregator/lib/Drupal/aggregator/Plugin/Core/Entity/Item.php
Contains \Drupal\aggregator\Plugin\Core\Entity\Item.
Node.php in drupal/core/modules/node/lib/Drupal/node/Plugin/Core/Entity/Node.php
Definition of Drupal\node\Plugin\Core\Entity\Node.
NodeAccessController.php in drupal/core/modules/node/lib/Drupal/node/NodeAccessController.php
Contains \Drupal\node\NodeAccessController.
Term.php in drupal/core/modules/taxonomy/lib/Drupal/taxonomy/Plugin/Core/Entity/Term.php
Definition of Drupal\taxonomy\Plugin\Core\Entity\Term.
translation_entity.module in drupal/core/modules/translation_entity/translation_entity.module
Allows entities to be translated into different languages.
translation_entity.pages.inc in drupal/core/modules/translation_entity/translation_entity.pages.inc
The entity translation user interface.
User.php in drupal/core/modules/user/lib/Drupal/user/Plugin/Core/Entity/User.php
Definition of Drupal\user\Plugin\Core\Entity\User.