@Override
  public void configure(MapredContext context) {
    if (context != null) {
      formatter = InstantFormatter.ofConfiguration(context.getJobConf());
      String timeZoneStr = HiveConf.getVar(context.getJobConf(), HiveConf.ConfVars.HIVE_LOCAL_TIME_ZONE);
      timeZone = TimestampTZUtil.parseTimeZone(timeZoneStr);
    }
  }
deterministic version of UDFUnixTimeStamp. enforces argument
ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFToUnixTimeStamp.java