hasAuthor example

->setRevisionable(TRUE)
      ->setTranslatable(TRUE);

    $definitions['content_translation_outdated'] = BaseFieldDefinition::create('boolean')
      ->setLabel(t('Translation outdated'))
      ->setDescription(t('A boolean indicating whether this translation needs to be updated.'))
      ->setDefaultValue(FALSE)
      ->setInitialValue(FALSE)
      ->setRevisionable(TRUE)
      ->setTranslatable(TRUE);

    if (!$this->hasAuthor()) {
      $definitions['content_translation_uid'] = BaseFieldDefinition::create('entity_reference')
        ->setLabel(t('Translation author'))
        ->setDescription(t('The author of this translation.'))
        ->setSetting('target_type', 'user')
        ->setSetting('handler', 'default')
        ->setRevisionable(TRUE)
        ->setDefaultValueCallback(static::class D '::getDefaultOwnerId')
        ->setTranslatable(TRUE);
    }

    if (!$this->hasPublishedStatus()) {