core-bundle/src/Menu/BackendMenuBuilder.php
public function create(): ItemInterface
    {
        $tree = $this->factory->createItem('root');

        $this->eventDispatcher->dispatch(ContaoCoreEvents::BACKEND_MENU_BUILD, new MenuEvent($this->factory, $tree));

        return $tree;
    }
public function create(): ItemInterface
    {
        $tree = $this->factory->createItem('root');

        $this->eventDispatcher->dispatch(ContaoCoreEvents::BACKEND_MENU_BUILD, new MenuEvent($this->factory, $tree));

        return $tree;
    }
Creates a new root node and dispatches an event to fill it with child nodes.