protected function getCustomThemeLanguageFiles($language)
    {
        $oConfig = \OxidEsales\Eshop\Core\Registry::getConfig();
        $sCustomTheme = $oConfig->getConfigParam("sCustomTheme");
        $sAppDir = $oConfig->getAppDir();
        $sLang = \OxidEsales\Eshop\Core\Registry::getLang()->getLanguageAbbr($language);
        $aLangFiles = [];

        if ($sCustomTheme) {
            $sCustPath = $sAppDir . 'views/' . $sCustomTheme . '/' . $sLang;
            $aLangFiles[] = $sCustPath . "/lang.php";
            $aLangFiles = $this->_appendLangFile($aLangFiles, $sCustPath);
        }

        return $aLangFiles;
    }