code: private SofaRpcException clientTimeoutWhenSendResponse(String appName, String serviceName, String remoteAddress) {
          String errorMsg = LogCodes.getLog(
              LogCodes.ERROR_DISCARD_TIMEOUT_RESPONSE, serviceName, remoteAddress);
          if (LOGGER.isWarnEnabled(appName)) {
              LOGGER.warnWithApp(appName, errorMsg);
          }
          return new SofaRpcException(RpcErrorType.SERVER_UNDECLARED_ERROR, errorMsg);
      }
docs: 客户端已经超时了（例如在业务执行时间太长），丢弃这个返回值
  
  @param appName       应用
  @param serviceName   服务
  @param remoteAddress 远程地址
  @return 丢弃的异常