code: public static VariableResolver getUpdateVariableResolver(ServletRequest request,
                                                               ServletResponse response,
                                                               boolean isHandlingPost) {
          Object form = ImplicitObjectUtil.unwrapForm(getActionForm(request));
          return new NetUIUpdateVariableResolver(form, request, response, isHandlingPost);
      }
docs: Internal method!
  
  Create a {@link VariableResolver} that contains the implicit objects available for expression
  updates.