public String formatTimeMillis(long ts) {
      synchronized (timeFormatter) {
        return timeFormatter.format(new Date(ts));
      }
    }
Formats an archive timestamp in way consistent with GemFire log dates. It will also be
formatted to reflect the time zone the archive was created in.

@param ts The difference, measured in milliseconds, between the time marked by this time
       stamp and midnight, January 1, 1970 UTC.
geode-core/src/main/java/org/apache/geode/internal/statistics/StatArchiveReader.java