buf.append(obj);
        } else if (obj instanceof Boolean) {
            buf.append(obj.toString());
        } else if (obj instanceof Date) {
            final SimpleDateFormat sdf = new SimpleDateFormat(CoreLibConstants.DATE_FORMAT_ISO_8601_EXTEND, Locale.ROOT);
            buf.append('\"').append(StringEscapeUtils.escapeJson(sdf.format(obj))).append('\"');
        } else {

        String createdStr;
        final Date created = DocumentUtil.getValue(doc, fessConfig.getIndexFieldCreated(), Date.class);
        if (created != null) {
            final SimpleDateFormat sdf = new SimpleDateFormat(CoreLibConstants.DATE_FORMAT_ISO_8601_EXTEND);
            createdStr = sdf.format(created);
        } else {

     *
     * @param value The date string to parse
     * @return The parsed date, or null if parsing fails
     */
    protected Date parseLastModifiedDate(final String value) {
        final SimpleDateFormat sdf = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z", Locale.ENGLISH);
        try {
            return sdf.parse(value);
        } catch (final ParseException e) {
            return null;
        }
    }