docs: public double getCouponPayment(int periodIndex, AnalyticModel model) {
  
  		ForwardCurve forwardCurve = model.getForwardCurve(forwardCurveName);
  		if(forwardCurve == null && forwardCurveName != null && forwardCurveName.length() > 0) {
  			throw new IllegalArgumentException("No forward curve with name '" + forwardCurveName + "' was found in the model:\n" + model.toString());
  		}
  
  		double periodLength	= schedule.getPeriodLength(periodIndex);
  		double couponPayment=fixedCoupon ;
  		if(forwardCurve != null ) {
  			couponPayment = floatingSpread+forwardCurve.getForward(model, schedule.getFixing(periodIndex));
  		}
  		return couponPayment*periodLength;
  	}