class MenuListBuilder

class MenuListBuilder extends ConfigEntityListBuilder {
  
  /**
   * {@inheritdoc}
   */
  protected function getEntityIds() {
    $query = $this->getStorage()
      ->getQuery()
      ->sort('label', 'ASC');
    // Only add the pager if a limit is specified.
    if ($this->limit) {
      $query->pager($this->limit);
    }
    return $query->execute();
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildHeader() {
    $header['title'] = t('Title');
    $header['description'] = [
      'data' => t('Description'),
      'class' => [
        RESPONSIVE_PRIORITY_MEDIUM,
      ],
    ];
    return $header + parent::buildHeader();
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildRow(EntityInterface $entity) {
    $row['title'] = [
      'data' => $entity->label(),
      'class' => [
        'menu-label',
      ],
    ];
    $row['description']['data'] = [
      '#markup' => $entity->getDescription(),
    ];
    return $row + parent::buildRow($entity);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getDefaultOperations(EntityInterface $entity) {
    $operations = parent::getDefaultOperations($entity);
    if (isset($operations['edit'])) {
      $operations['edit']['title'] = t('Edit menu');
      $operations['add'] = [
        'title' => t('Add link'),
        'weight' => 20,
        'url' => $entity->toUrl('add-link-form'),
        'query' => [
          'destination' => $entity->toUrl('edit-form')
            ->toString(),
        ],
      ];
    }
    if (isset($operations['delete'])) {
      $operations['delete']['title'] = t('Delete menu');
    }
    return $operations;
  }
  
  /**
   * {@inheritdoc}
   */
  protected function ensureDestination(Url $url) {
    // We don't want to add the destination URL here, as it means we get
    // redirected back to the list-builder after adding/deleting menu links from
    // a menu.
    return $url;
  }
  
  /**
   * {@inheritdoc}
   */
  public function render() {
    $build = parent::render();
    $build['#attached']['library'][] = "menu_ui/drupal.menu_ui.adminforms";
    return $build;
  }

}