code: private long getLastTimeStamp() {
      long result = -1;
      if (coronaReleaseFileCheck != null && !coronaReleaseFileCheck.isEmpty()) {
        result = getLastTimeStamp(new Path(releasePath, coronaReleaseFileCheck));
        if (result > 0) {
          return result;
        }
      }
      return getLastTimeStamp(releasePath);
    }
docs: getLastStamp will go throught all the files and directories in the release
  directory, and find the largest timestamp. This is used to check if there
  is any new release. RELEASE_COPY_PATTERN and CORONA_RELEASE_FILE_CHECK can
  be used to limit the files checked