private static String pad(int length, long v) {
    StringBuilder s = new StringBuilder(Long.toString(v));
    while (s.length() < length) {
      s.insert(0, "0");
    }
    return s.toString();
  }
Returns the value of the argument as an unsigned integer in seconds since '1970-01-01 00:00:00'
UTC.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/util/DateTimeUtils.java