public InventoryOrderModel SubmitOrder(InventoryOrderModel order)
        {
            // authorize user
            //TODO authorization

            // convert to valid input
            var incomingOrder = new InventoryOrder();

            foreach (var orderLine in order.Contents)
            {
                incomingOrder.Contents.Add(new InventoryOrderLine(orderLine.Warehouse, orderLine.Product, orderLine.Quantity));
            }

            // validate input
            //TODO validation

            // submit + map result
            var updatedOrder = _backend.SubmitOrder(incomingOrder);

            return(new InventoryOrderModel(updatedOrder));
        }