public void set(TimestampTZ tstz) {
    if (tstz == null) {
      timestampTZ.setZonedDateTime(null);
      return;
    }
    timestampTZ.setZonedDateTime(tstz.getZonedDateTime());
    timeZone = timestampTZ.getZonedDateTime().getZone();
    bytesEmpty = true;
    timestampTZEmpty = false;
  }
true if data is stored in timestamptz field rather than byte arrays.
allows for lazy conversion to bytes when necessary
false otherwise
serde/src/java/org/apache/hadoop/hive/serde2/io/TimestampLocalTZWritable.java