code: private long getLastTimeStamp(Path pathToCheck) {
      long lastTimeStamp = -1;
      long tmpTimeStamp = -1;
      try {
        for (FileStatus fileStat: fs.listStatus(pathToCheck)) {
          Path srcPath = fileStat.getPath();
          if (!fileStat.isDir()) {
            boolean checkFlag = true;
            if (release_pattern != null) {
              // just need to check the files that match the pattern
              Matcher m = release_pattern.matcher(srcPath.toString());
              if (!m.find()) {
                checkFlag = false;
              } 
            }
            if (checkFlag) {
              tmpTimeStamp = fileStat.getModificationTime();
            } else {
              continue;
            }
          } else {
            tmpTimeStamp = getLastTimeStamp(srcPath);
          }
          if (tmpTimeStamp > lastTimeStamp) {
            lastTimeStamp = tmpTimeStamp;
          }
        }
      } catch (IOException ioe) {
        LOG.error("IOException when checking timestamp ", ioe);
      }
      return lastTimeStamp;
    }
docs: Get the release directory's latest timestamp