获取回调失败的结果与文档不符合

corpId：    dingb40b8a19b6ded94235c2f4657eb6378f


接口名称：    https  ://  oapi.dingtalk.com/  call_back/get_call_back_failed_result
接口参数：    DingTalkClient client = new DefaultDingTalkClient("https://oapi.dingtalk.com/call_back/get_call_back_failed_result");
                        OapiCallBackGetCallBackFailedResultRequest request = new OapiCallBackGetCallBackFailedResultRequest();
                        request.setHttpMethod("GET");
                        OapiCallBackGetCallBackFailedResultResponse response = client.execute(request,accessToken);
返回的结果中的 [font="]FailedList实际如下
{"call_back_tag":"user_modify_org","event_time":1535028105000,"user_modify_org":"{corpid=dingb40b8a19b6ded94235c2f4657eb6378f}"}
{"call_back_tag":"user_modify_org","event_time":1535028150000,"user_modify_org":"{corpid=dingb40b8a19b6ded94235c2f4657eb6378f}"}
从返回的结果中无法获取userId无法做失败补偿
求问回调失败结果该如何处理