final JsonRequestParams params = new JsonRequestParams(request, fessConfig);
        try {
            response.setContentType("application/x-ndjson; charset=UTF-8");
            final long count = searchHelper.scrollSearch(params, doc -> {
                buf.setLength(0);
                buf.append('{');
                boolean first2 = true;
                for (final Map.Entry<String, Object> entry : doc.entrySet()) {