// Starts 'chaining' load of customers, orders, orderdetails.
        private void LoadCustomers(string name = null)
        {
            Customers.Clear();

            // Either get all customers or filter by name.
            if (string.IsNullOrEmpty(name))
            {
                context.Load(context.GetCustomersQuery(), GetCustomersQueryCallback, true);
            }
            else
            {
                context.Load(context.FindCustomersQuery(name), GetCustomersQueryCallback, true);
            }
        }