SqlEntityStorageInterface

class \Drupal\Core\Entity\Sql\SqlContentEntityStorage extends \Drupal\Core\Entity\ContentEntityStorageBase implements \Drupal\Core\Entity\Sql\SqlEntityStorageInterface, \Drupal\Core\Entity\Schema\DynamicallyFieldableEntityStorageSchemaInterface, \Drupal\Core\Entity\EntityBundleListenerInterface
class \Drupal\user\UserStorage extends \Drupal\Core\Entity\Sql\SqlContentEntityStorage implements \Drupal\user\UserStorageInterface

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