code: public void invoke(HttpServletRequest req, HttpServletResponse rsp, Object root, String url) throws IOException, ServletException {
          RequestImpl sreq = new RequestImpl(this, req, new ArrayList<AncestorImpl>(), new TokenList(url));
          RequestImpl oreq = CURRENT_REQUEST.get();
          CURRENT_REQUEST.set(sreq);
  
          ResponseImpl srsp = new ResponseImpl(this, rsp);
          ResponseImpl orsp = CURRENT_RESPONSE.get();
          CURRENT_RESPONSE.set(srsp);
  
          try {
              invoke(sreq,srsp,root);
          } finally {
              CURRENT_REQUEST.set(oreq);
              CURRENT_RESPONSE.set(orsp);
          }
      }
docs: Performs stapler processing on the given root object and request URL.