private static long firstMondayOfFirstWeek(int year) {
    long janFirst = ymdToJulian(year, 1, 1);
    long janFirstDow = floorMod(janFirst + 1L, 7L);
    return janFirst + (11L - janFirstDow) % 7L - 3L;
  }
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