docs: public Interval overlap(ReadableInterval interval) {
          interval = DateTimeUtils.getReadableInterval(interval);
          if (overlaps(interval) == false) {
              return null;
          }
          long start = Math.max(getStartMillis(), interval.getStartMillis());
          long end = Math.min(getEndMillis(), interval.getEndMillis());
          return new Interval(start, end, getChronology());
      }