final List<org.codelibs.fess.crawler.client.http.RequestHeader> rhList = new ArrayList<>();
        for (final RequestHeader requestHeader : requestHeaderList) {
            rhList.add(requestHeader.getCrawlerRequestHeader());
        }
        paramMap.put(HcHttpClient.REQUEST_HEADERS_PROPERTY,
                rhList.toArray(new org.codelibs.fess.crawler.client.http.RequestHeader[rhList.size()]));