code: private void updateDownloadStatus(S3Object result) {
          if (result == null) {
              download.setState(Transfer.TransferState.Canceled);
              download.setMonitor(new DownloadMonitor(download, null));
          } else {
              download.setState(Transfer.TransferState.Completed);
          }
      }
docs: Takes the result from serial download,
  updates the transfer state and monitor in downloadImpl object
  based on the result.