class DeleteForm

class DeleteForm extends ContentEntityDeleteForm {
  
  /**
   * {@inheritdoc}
   */
  public function getCancelUrl() {
    // Point to the entity of which this comment is a reply.
    return $this->entity
      ->get('entity_id')->entity
      ->toUrl();
  }
  
  /**
   * {@inheritdoc}
   */
  protected function getRedirectUrl() {
    return $this->getCancelUrl();
  }
  
  /**
   * {@inheritdoc}
   */
  public function getDescription() {
    return $this->t('Any replies to this comment will be lost. This action cannot be undone.');
  }
  
  /**
   * {@inheritdoc}
   */
  protected function getDeletionMessage() {
    return $this->t('The comment and all its replies have been deleted.');
  }
  
  /**
   * {@inheritdoc}
   */
  public function logDeletionMessage() {
    $this->logger('comment')
      ->info('Deleted comment @cid and its replies.', [
      '@cid' => $this->entity
        ->id(),
    ]);
  }

}