protected function convertHierachicalResources(&$resources)
    {
        foreach ($resources as &$resource) {
            if (gettype($resource)=="string") {
                $resource = $this->getAssetManager()->getAssetUrl($resource);
            } else if (gettype($resource)=="array") {
                $this->convertHierachicalResources($resource);
            }
        }
        return $resources;
    }