// request header
        final List<RequestHeader> requestHeaderList = requestHeaderService.getRequestHeaderList(getId());
        final List<org.codelibs.fess.crawler.client.http.RequestHeader> rhList = new ArrayList<>();
        for (final RequestHeader requestHeader : requestHeaderList) {

                    appendJson("search-field", searchFieldMap, buf).append(',');
                    final Map<String, List<String>> requestHeaderMap = entity.getRequestHeaderList().stream()
                            .collect(Collectors.groupingBy(Pair::getFirst, Collectors.mapping(Pair::getSecond, Collectors.toList())));
                    appendJson("headers", requestHeaderMap, buf);