code: protected void setInterval(long startInstant, long endInstant, Chronology chrono) {
          checkInterval(startInstant, endInstant);
          iStartMillis = startInstant;
          iEndMillis = endInstant;
          iChronology = DateTimeUtils.getChronology(chrono);
      }
docs: Sets this interval from two millisecond instants and a chronology.
  
  @param startInstant  the start of the time interval
  @param endInstant  the start of the time interval
  @param chrono  the chronology, not null
  @throws IllegalArgumentException if the end is before the start