public function supportedLocale($sValue)
    {
        /** @var Locale $oLocale */
        $oLocale           = Factory::service('Locale');
        $aSupportedLocales = $oLocale->getSupportedLocales();
        if (!in_array($sValue, $aSupportedLocales)) {
            $this->set_message('supportedLocale', 'This is not a supported locale');
            return false;
        }

        return true;
    }