code: public Duration<IsoUnit> getNominalDuration(
          Timezone tz,
          IsoUnit... units
      ) {
  
          return this.toZonalInterval(tz.getID()).getDuration(tz, units);
  
      }
docs: /*[deutsch]
  <p>Liefert die nominelle Dauer dieses Intervalls in der angegebenen Zeitzone
  und den angegebenen Zeiteinheiten. </p>
  
  @param   tz          timezone
  @param   units       time units to be used in calculation
  @return  nominal duration
  @throws  UnsupportedOperationException if this interval is infinite
  @since   3.0
  @see     #getSimpleDuration()
  @see     #getRealDuration()