class SystemMenuBlock

class SystemMenuBlock extends DeriverBase implements ContainerDeriverInterface {
  
  /**
   * The menu storage.
   *
   * @var \Drupal\Core\Entity\EntityStorageInterface
   */
  protected $menuStorage;
  
  /**
   * Constructs new SystemMenuBlock.
   *
   * @param \Drupal\Core\Entity\EntityStorageInterface $menu_storage
   *   The menu storage.
   */
  public function __construct(EntityStorageInterface $menu_storage) {
    $this->menuStorage = $menu_storage;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, $base_plugin_id) {
    return new static($container->get('entity_type.manager')
      ->getStorage('menu'));
  }
  
  /**
   * {@inheritdoc}
   */
  public function getDerivativeDefinitions($base_plugin_definition) {
    foreach ($this->menuStorage
      ->loadMultiple() as $menu => $entity) {
      $this->derivatives[$menu] = $base_plugin_definition;
      $this->derivatives[$menu]['admin_label'] = $entity->label();
      $this->derivatives[$menu]['config_dependencies']['config'] = [
        $entity->getConfigDependencyName(),
      ];
    }
    return $this->derivatives;
  }

}