code: public void setEnd(ReadableInstant end) {
          long endMillis = DateTimeUtils.getInstantMillis(end);
          super.setInterval(getStartMillis(), endMillis, getChronology());
      }
docs: Sets the end of this time interval as an Instant.
  
  @param end  the end of the time interval, null means now
  @throws IllegalArgumentException if the end is before the start