private static Map<Pair<TimeUnit>, TimeUnitRange> createMap() {
      Map<Pair<TimeUnit>, TimeUnitRange> map = new HashMap<>();
      for (TimeUnitRange value : values()) {
        map.put(new Pair<>(value.startUnit, value.endUnit), value);
      }
      return Collections.unmodifiableMap(map);
    }
Returns a {@code TimeUnitRange} with a given start and end unit.

@param startUnit Start unit
@param endUnit End unit
@return Time unit range, or null if not valid
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/util/DateTimeUtils.java