ContentEntityDeleteForm::buildForm

public ContentEntityDeleteForm::buildForm(array $form, FormStateInterface $form_state)

public function buildForm(array $form, FormStateInterface $form_state) {
  $form = parent::buildForm($form, $form_state);

  /** @var \Drupal\Core\Entity\ContentEntityInterface $entity */
  $entity = $this->getEntity();
  if ($entity->isDefaultTranslation()) {
    if (count($entity->getTranslationLanguages()) > 1) {
      $languages = [];
      foreach ($entity->getTranslationLanguages() as $language) {
        $languages[] = $language->getName();
      }

      $form['deleted_translations'] = array(
        '#theme' => 'item_list',
        '#title' => $this->t('The following @entity-type translations will be deleted:', [
          '@entity-type' => $entity->getEntityType()->getLowercaseLabel()
        ]),
        '#items' => $languages,
      );

      $form['actions']['submit']['#value'] = $this->t('Delete all translations');
    }
  }
  else {
    $form['actions']['submit']['#value'] = $this->t('Delete @language translation', array('@language' => $entity->language()->getName()));
  }

  return $form;
}