All classes that implement EntityTypeInterface in Drupal 9
- class \Drupal\Core\Config\Entity\ConfigEntityType implements ConfigEntityTypeInterface
- class \Drupal\Core\Entity\ContentEntityType implements ContentEntityTypeInterface
- class \Drupal\Core\Entity\EntityType implements EntityTypeInterface uses DependencySerializationTrait, StringTranslationTrait
- class \Drupal\Tests\views\Unit\TestEntityType