code: public function process(ContainerBuilder $container)
      {
          if (!$container->has('netgen_admin_ui.menu_plugin.registry')) {
              return;
          }
  
          $menuPluginRegistry = $container->findDefinition('netgen_admin_ui.menu_plugin.registry');
          $menuPlugins = $container->findTaggedServiceIds('netgen_admin_ui.menu_plugin');
  
          $flattenedMenuPlugins = array();
          foreach ($menuPlugins as $identifier => $menuPlugin) {
              $flattenedMenuPlugins[$identifier] = isset($menuPlugin[0]['priority']) ? $menuPlugin[0]['priority'] : 0;
          }
  
          arsort($flattenedMenuPlugins);
  
          foreach (array_keys($flattenedMenuPlugins) as $menuPlugin) {
              $menuPluginRegistry->addMethodCall(
                  'addMenuPlugin',
                  array(new Reference($menuPlugin))
              );
          }
      }
docs: Registers all menu plugins in the plugin registry.
  
  @param \Symfony\Component\DependencyInjection\ContainerBuilder $container