public override int GetHashCode() { var hashCode = -2027619230; hashCode = hashCode * -1521134295 + ProductID.GetHashCode(); hashCode = hashCode * -1521134295 + EqualityComparer <string> .Default.GetHashCode(ProductName); hashCode = hashCode * -1521134295 + ProductPrice.GetHashCode(); hashCode = hashCode * -1521134295 + ProductQuantity.GetHashCode(); return(hashCode); }