code: private static String getHistoryFileUrl(RetireJobInfo info) {
      String historyFile = info.getHistoryFile();
      String historyFileUrl = null;
      if (historyFile != null && !historyFile.equals("")) {
        try {
          historyFileUrl = URLEncoder.encode(info.getHistoryFile(), "UTF-8");
        } catch (UnsupportedEncodingException e) {
          LOG.warn("Can't create history url ", e);
        }
      }
      return historyFileUrl;
    }
docs: Obtain history file URL from RetireJobInfo
  @param info RetireJobInfo
  @return corresponding history file url, null if cannot creat one