final String id = (String) source.remove(fessConfig.getIndexFieldId());
        source.remove(fessConfig.getIndexFieldVersion());
        final Number seqNo = (Number) source.remove(fessConfig.getIndexFieldSeqNo());
        final Number primaryTerm = (Number) source.remove(fessConfig.getIndexFieldPrimaryTerm());
        IndexResponse response;
        try {
            if (id == null) {

            buf.append(escapeJson(nextPage));
            buf.append(",\"prev_page\":");
            buf.append(escapeJson(prevPage));
            buf.append(",\"start_record_number\":");
            buf.append(startRecordNumber);
            buf.append(",\"end_record_number\":");
            buf.append(escapeJson(endRecordNumber));
            buf.append(",\"page_numbers\":");
            buf.append(escapeJson(pageNumbers));