private static long toMillis(DecimalData v) {
    return v.toBigDecimal().setScale(0, RoundingMode.DOWN).longValue();
  }
Converts the Java type used for UDF parameters of SQL TIMESTAMP type ({@link Timestamp}) to
internal representation (long).

<p>Converse of {@link #toSQLTimestamp(long)}.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/util/DateTimeUtils.java