TranslationInterface

class \Drupal\Core\StringTranslation\TranslationManager implements \Drupal\Core\StringTranslation\TranslationInterface, \Drupal\Core\StringTranslation\Translator\TranslatorInterface
class \Drupal\Tests\Core\StringTranslation\TestTranslationManager extends \Drupal\Core\StringTranslation\TranslationManager
class \Drupal\Tests\user\Unit\TestTranslationManager implements \Drupal\Core\StringTranslation\TranslationInterface

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