code: public Interval withChronology(Chronology chronology) {
          if (getChronology() == chronology) {
              return this;
          }
          return new Interval(getStartMillis(), getEndMillis(), chronology);
      }
docs: Creates a new interval with the same start and end, but a different chronology.
  
  @param chronology  the chronology to use, null means ISO default
  @return an interval with a different chronology