code: public function getMenu(): ItemInterface
      {
          if (null !== $this->menu) {
              return $this->menu;
          }
  
          $this->menu = $this->menuFactory->createItem('picker');
  
          foreach ($this->providers as $provider) {
              $this->menu->addChild($provider->createMenuItem($this->config));
          }
  
          return $this->menu;
      }
docs: {@inheritdoc}