docs: public boolean success(long msgId) {
  		String url = WxEndpoint.get("url.mass.message.status");
  		String request = "{\"msg_id\":%s}";
  
  		logger.debug("check message sending status: {}", msgId);
  		String response = wxClient.post(url, String.format(request, msgId));
  		Map<String, Object> map = JsonMapper.defaultMapper().json2Map(response);
  		return map.containsKey("msg_status") && "SEND_SUCCESS".equalsIgnoreCase(map.get("msg_status").toString());
  	}