Non-nullable property 'Items' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.

Non-nullable property 'Product' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.

Non-nullable property 'Items' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.