code: public static Waehrung of(CurrencyUnit currencyUnit) {
          if (currencyUnit instanceof Waehrung) {
              return (Waehrung) currencyUnit;
          } else {
              return of(currencyUnit.getCurrencyCode());
          }
      }
docs: Gibt die entsprechende Currency als Waehrung zurueck.
  
  @param currencyUnit CurrencyUnit
  @return Waehrung