public static long convertTimeToProleptic(long hybrid) {
    long proleptic = hybrid;
    if (hybrid < SWITCHOVER_MILLIS) {
      String dateStr = HYBRID_TIME_FORMAT.get().format(new Date(hybrid));
      try {
        proleptic = PROLEPTIC_TIME_FORMAT.get().parse(dateStr).getTime();
      } catch (ParseException e) {
        throw new IllegalArgumentException("Can't parse " + dateStr, e);
      }
    }
    return proleptic;
  }
Convert epoch millis from the hybrid Julian/Gregorian calendar to the
proleptic Gregorian.
@param hybrid millis of epoch in the hybrid Julian/Gregorian
@return millis of epoch in the proleptic Gregorian
storage-api/src/java/org/apache/hadoop/hive/common/type/CalendarUtils.java