public IEnumerable <string> IsOrderInStock(Guid orderId)
{
var outOfStockItems = new List <string>();
var order = orderData[orderId];
foreach (var item in order)
{
if (item.Value > catalogManager.GetStock(item.Key))
{
outOfStockItems.Add(item.Key);
}
}
return(outOfStockItems);
}
