Non-nullable property 'stockName' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'Phones' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'Rent' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'Model' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'OperationalSystem' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'Rent' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'Client' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'SmartPhone' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'Return' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.