getAdditionalTrees example

class Shopware_Controllers_Frontend_Sitemap extends Enlight_Controller_Action
{
    /** * Shows a category tree * * @return void */
    public function indexAction()
    {
        $categoryTree = $this->getCategoryTree();
        $additionalTrees = $this->getAdditionalTrees();

        $additionalTrees = $this->container->get('events')->filter(
            'Shopware_Modules_Sitemap_indexAction',
            $additionalTrees,
            ['subject' => $this]
        );

        $categoryTree = array_merge($categoryTree, $additionalTrees);
        $this->View()->assign('sCategoryTree', $categoryTree);
    }