Drug order is not allowed without a drug - TRUNK-4437
Drug orders for different formulations of the same concept should be allowed - TRUNK-4436

TRUNK-4436: Improve the order service test and use nullSafeEquals

TRUNK-4436: Use nullSafeEquals in Order
Follow up to clean up unit tests - TRUNK-4436

Follow up to clean up unit tests - TRUNK-4436

Follow up to clean up unit tests - TRUNK-4436