code: @Override
      public String post_xml(String path, String xml_data, boolean crumbFlag) throws IOException {
          HttpPost request = new HttpPost(UrlUtils.toJsonApiUri(uri, context, path));
          handleCrumbFlag(crumbFlag, request);
  
          if (xml_data != null) {
              request.setEntity(new StringEntity(xml_data, ContentType.create("text/xml", "utf-8")));
          }
          HttpResponse response = client.execute(request, localContext);
          jenkinsVersion = ResponseUtils.getJenkinsVersion(response);
          try {
              httpResponseValidator.validateResponse(response);
              return IOUtils.toString(response.getEntity().getContent());
          } finally {
              EntityUtils.consume(response.getEntity());
              releaseConnection(request);
          }
      }
docs: {@inheritDoc}