docs: @WebMethod(name = "config.xml")
      public void doConfigDotXml(StaplerRequest req, StaplerResponse rsp)
              throws IOException {
          if (req.getMethod().equals("GET")) {
              // read
              rsp.setContentType("application/xml");
              writeConfigDotXml(rsp.getOutputStream());
              return;
          }
          if (req.getMethod().equals("POST")) {
              // submission
              updateByXml((Source)new StreamSource(req.getReader()));
              return;
          }
  
          // huh?
          rsp.sendError(SC_BAD_REQUEST);
      }