private static long powerX(long a, long b) {
    long x = 1;
    while (b > 0) {
      x *= a;
      --b;
    }
    return x;
  }
Helper for CAST({date} AS VARCHAR(n)).
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/util/DateTimeUtils.java