code: private static String prefixForTimestamp(DateTime timestamp) {
          return String.format("monsoon-%04d%02d%02d-%02d%02d", timestamp.getYear(), timestamp.getMonthOfYear(), timestamp.getDayOfMonth(), timestamp.getHourOfDay(), timestamp.getMinuteOfHour());
      }
docs: Compute a prefix for a to-be-installed file.
  
  @param timestamp the timestamp on which to base the prefix.
  @return a file prefix that represents the timestamp in its name.