protected function doFindLocalizedAsset($locale, $asset)
    {
        if (isset($this->assets[$locale][$asset])) {
            return $this->assets[$locale][$asset];
        }

        if (0 < $pos = strpos($locale, '_')) {
            return $this->doFindLocalizedAsset(substr($locale, 0, $pos), $asset);
        }

        return [];
    }