MenuLinkPluginConverter.php

<?php

namespace Drupal\Core\ParamConverter;

use Drupal\Core\Menu\MenuLinkManagerInterface;
use Drupal\Component\Plugin\Exception\PluginException;
use Symfony\Component\Routing\Route;

/**
 * Parameter converter for upcasting entity ids to full objects.
 */
class MenuLinkPluginConverter implements ParamConverterInterface {
    
    /**
     * Plugin manager which creates the instance from the value.
     *
     * @var \Drupal\Core\Menu\MenuLinkManagerInterface
     */
    protected $menuLinkManager;
    
    /**
     * Constructs a new MenuLinkPluginConverter.
     *
     * @param \Drupal\Core\Menu\MenuLinkManagerInterface $menu_link_manager
     *   The menu link plugin manager.
     */
    public function __construct(MenuLinkManagerInterface $menu_link_manager) {
        $this->menuLinkManager = $menu_link_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public function convert($value, $definition, $name, array $defaults) {
        if ($value) {
            try {
                return $this->menuLinkManager
                    ->createInstance($value);
            } catch (PluginException $e) {
                // Suppress the error.
            }
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function applies($definition, $name, Route $route) {
        return !empty($definition['type']) && $definition['type'] === 'menu_link_plugin';
    }

}