public UserVendingMachineAggregationEntity(VendingMachineEntity vendingMachine, UserEntity user)
        {
            Contract.Requires(vendingMachine != null);
            Contract.Requires(user != null);

            VendingMachine = vendingMachine;
            User           = user;
        }
        public UserVendingMachineAggregationEntity(VendingMachineEntity vendingMachine, UserEntity user)
        {
            Contract.Requires(vendingMachine != null);
            Contract.Requires(user != null);

            VendingMachine = vendingMachine;
            User = user;
        }