@Override
protected Money subtractFromExemptions(Event event, DateTime when, boolean applyDiscount, Money amountToPay) {
if (event instanceof AcademicEvent) {
final AcademicEvent requestEvent = (AcademicEvent) event;
if (requestEvent.hasAcademicEventExemption()) {
amountToPay = amountToPay.subtract(requestEvent.getAcademicEventExemption().getValue());
}
return amountToPay.isPositive() ? amountToPay : Money.ZERO;
}