Entity.cs

public class ShoppingCart
{
    public ShoppingCart(Guid shoppingCartId, Guid customerId)
    {
        ShoppingCartId = shoppingCartId;
        CustomerId = customerId;
    }

    public Guid ShoppingCartId { get; private set; }
    public Guid CustomerId { get; private set; }
    public IList<ShoppingCartItem> Items { get; set; } = new List<ShoppingCartItem>();
}

public class ShoppingCartItem
{
    public ShoppingCartItem(Guid shoppingCartId, Guid productId, int quantity, decimal price)
    {
        ShoppingCartId = shoppingCartId;
        ProductId = productId;
        Quantity = quantity;
        Price = price;
    }

    public Guid ShoppingCartId { get; set; }
    public Guid ProductId { get; private set; }
    public int Quantity { get; set; }
    public decimal Price { get; private set; }
}