@Override
  protected long getTimestampField(TimestampColumnVector timestampColVector, int elementNum) {
    java.sql.Timestamp ts = timestampColVector.asScratchTimestamp(elementNum);
    timestamp.setTimeInMillis(ts.getTime(), ts.getNanos());
    return TimestampTZUtil.convert(timestamp, timeZone).getEpochSecond();
  }
Return Unix Timestamp.
Extends {@link VectorUDFTimestampFieldTimestamp}
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/VectorUDFUnixTimeStampTimestamp.java