* @param serialNumber The serial number of the notification to fetch.
* @return The notification corresponding to the serial number.
* @throws CheckoutException If underlying communication throws an exception.
*/
public Notification requestNotification(String serialNumber) throws CheckoutException {
NotificationHistoryRequest request = new NotificationHistoryRequest();
request.setSerialNumber(serialNumber);
// this is a specific notification domain object.
return (Notification)postRequest(request.toJAXB());
}