Devise\Menus\MenusRepository::menuStructure PHP Method

    public function menuStructure($menu, $isRootMenu = true)
    {
        $structure = [];
        $items = $isRootMenu ? $menu->items : $menu->children;
        foreach ($items as $item) {
            $children = $this->menuStructure($item, false);
            $structure[$item->name] = $children ?: $item->url;
        }
        return $structure;
    }