class Menu

class Menu extends ConfigEntityBase implements MenuInterface {
    
    /**
     * The menu machine name.
     *
     * @var string
     */
    protected $id;
    
    /**
     * The human-readable name of the menu entity.
     *
     * @var string
     */
    protected $label;
    
    /**
     * The menu description.
     *
     * @var string
     */
    protected $description;
    
    /**
     * The locked status of this menu.
     *
     * @var bool
     */
    protected $locked = FALSE;
    
    /**
     * {@inheritdoc}
     */
    public function getDescription() {
        return $this->description;
    }
    
    /**
     * {@inheritdoc}
     */
    public function isLocked() {
        return (bool) $this->locked;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function preDelete(EntityStorageInterface $storage, array $entities) {
        parent::preDelete($storage, $entities);
        
        /** @var \Drupal\Core\Menu\MenuLinkManagerInterface $menu_link_manager */
        $menu_link_manager = \Drupal::service('plugin.manager.menu.link');
        foreach ($entities as $menu) {
            // Delete all links from the menu.
            $menu_link_manager->deleteLinksInMenu($menu->id());
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function save() {
        $return = parent::save();
        \Drupal::cache('menu')->invalidateAll();
        // Invalidate the block cache to update menu-based derivatives.
        if (\Drupal::moduleHandler()->moduleExists('block')) {
            \Drupal::service('plugin.manager.block')->clearCachedDefinitions();
        }
        return $return;
    }
    
    /**
     * {@inheritdoc}
     */
    public function delete() {
        parent::delete();
        \Drupal::cache('menu')->invalidateAll();
        // Invalidate the block cache to update menu-based derivatives.
        if (\Drupal::moduleHandler()->moduleExists('block')) {
            \Drupal::service('plugin.manager.block')->clearCachedDefinitions();
        }
    }

}