code: public static List<Kontonummer> getKontonummerList(int length) {
  		final class NormalKontonrDigitGenerator extends KontonummerDigitGenerator {
  			@Override
  			String generateKontonummer() {
  				StringBuilder kontonrBuffer = new StringBuilder(LENGTH);
  				for (int i = 0; i < LENGTH; i++) {
  					kontonrBuffer.append((int) (Math.random() * 10));
  				}
  				return kontonrBuffer.toString();
  			}
  		}
  		return getKontonummerListUsingGenerator(new NormalKontonrDigitGenerator(), length);
  	}
docs: Returns a List with completely random but syntactically valid Kontonummer
  instances.
  
  @param length
  Specifies the number of Kontonummer instances to create in the
  returned List
  
  @return A List with random valid Kontonummer instances