code: public Duration<ClockUnit> getDuration() {
  
          PlainTime t1 = this.getTemporalOfClosedStart();
          PlainTime t2 = this.getEnd().getTemporal();
  
          if (this.getEnd().isClosed()) {
              if (t2.getHour() == 24) {
                  if (t1.equals(PlainTime.midnightAtStartOfDay())) {
                      return Duration.of(24, HOURS).plus(1, NANOS);
                  } else {
                      t1 = t1.minus(1, NANOS);
                  }
              } else {
                  t2 = t2.plus(1, NANOS);
              }
          }
  
          return Duration.inClockUnits().between(t1, t2);
  
      }
docs: /*[deutsch]
  <p>Liefert die L&auml;nge dieses Intervalls. </p>
  
  @return  duration in hours, minutes, seconds and nanoseconds
  @since   2.0