code: public String getCardNumber() {
  		String ret = null;
  		if (track2 != null) {
  			ret = track2.getCardNumber();
  		}
  		if (ret == null && track1 != null) {
  			ret = track1.getCardNumber();
  		}
  		return ret;
  	}
docs: Method used to get the field cardNumber
  
  @return the cardNumber