CommentAdminOverview::submitForm

public CommentAdminOverview::submitForm(array &$form, FormStateInterface $form_state)

public function submitForm(array &$form, FormStateInterface $form_state) {
  $operation = $form_state->getValue('operation');
  $cids = $form_state->getValue('comments');

  foreach ($cids as $cid) {
    // Delete operation handled in \Drupal\comment\Form\ConfirmDeleteMultiple
    // see \Drupal\comment\Controller\AdminController::adminPage().
    if ($operation == 'unpublish') {
      $comment = $this->commentStorage->load($cid);
      $comment->setPublished(FALSE);
      $comment->save();
    }
    elseif ($operation == 'publish') {
      $comment = $this->commentStorage->load($cid);
      $comment->setPublished(TRUE);
      $comment->save();
    }
  }
  drupal_set_message($this->t('The update has been performed.'));
  $form_state->setRedirect('comment.admin');
}