code: private Chronology selectChronology(Chronology chrono) {
          chrono = DateTimeUtils.getChronology(chrono);
          if (iChrono != null) {
              chrono = iChrono;
          }
          if (iZone != null) {
              chrono = chrono.withZone(iZone);
          }
          return chrono;
      }
docs: Determines the correct chronology to use.
  
  @param chrono  the proposed chronology
  @return the actual chronology