*/
    protected StringBuilder appendTimestamp(final StringBuilder buf) {
        final SystemHelper systemHelper = ComponentUtil.getSystemHelper();
        append(buf, "timestamp", () -> FessFunctions.formatDate(systemHelper.getCurrentTime()));
        return buf;
    }

    /**
     * Appends exception information to the buffer.
     *
     * @param buf the string buffer to append to
     * @param exception the exception to append

        final String indexFieldLang = fessConfig.getIndexFieldLang();
        final List<String> guestRoleList = fessConfig.getSearchGuestRoleList();
        final Date now = systemHelper.getCurrentTime();
        final CrawlingInfoHelper crawlingInfoHelper = ComponentUtil.getCrawlingInfoHelper();
        final LanguageHelper languageHelper = ComponentUtil.getLanguageHelper();

        // segment
        defaultDataMap.put(fessConfig.getIndexFieldSegment(), initParamMap.getAsString(Constants.SESSION_ID));
        // created
        defaultDataMap.put(fessConfig.getIndexFieldCreated(), systemHelper.getCurrentTime());
        // boost
        defaultDataMap.put(fessConfig.getIndexFieldBoost(), config.getBoost().toString());
        // label: labelType
        // role: roleType