/// <summary>
/// add a contract for the supply of this product with
/// a specified supplier
/// </summary>
/// <param name="supplier">the supplier</param>
/// <param name="supplyPrice">the price charged by the supplier</param>
public void AddSupplier(Supplier supplier, decimal supplyPrice)
{
Contract contract = new Contract
{
Supplier = supplier,
SupplyPrice = supplyPrice,
Product = this
};
suppliers.Add(contract);
supplier.AddProduct(contract);
}
