final Locale locale = ComponentUtil.getRequestManager().getUserLocale();
        if (locale != null) {
            final String lang = locale.getLanguage();
            if (ComponentUtil.getFessConfig().isOnlineHelpSupportedLang(lang)) {
                target = lang.toUpperCase(Locale.ROOT);
            }
        }
        return url.replaceFirst("\\{lang\\}", target == null ? "EN" : target);
    }

    /**