code: public function onBuild(MenuEvent $event): void
      {
          if (null === $this->managerPath || !$this->isAdminUser()) {
              return;
          }
  
          $categoryNode = $event->getTree()->getChild('system');
  
          if (null === $categoryNode) {
              return;
          }
  
          $item = $event->getFactory()->createItem(
              'contao_manager',
              [
                  'label' => 'Contao Manager',
                  'attributes' => [
                      'title' => 'Contao Manager',
                      'href' => '/'.$this->managerPath,
                      'class' => 'navigation contao_manager',
                  ],
              ]
          );
  
          $categoryNode->addChild($item);
      }
docs: Adds a link to the Contao Manager in the back end navigation.