PropertyDeclarationSyntax MakeWriterRefTypeProperty( TypeSyntax type, string name, ExpressionSyntax getter, ExpressionSyntax setter, bool cast, bool cond) { if (cond) { type = _names.MakeNullableRefType(type); } var prop = MakeWriterProperty(type, name, getter, setter, cast, cond); if (cond && _names.NullableEnable) { prop = prop.AddAttributeLists( AttributeList( SingletonSeparatedList( Attribute( IdentifierName("DisallowNull"))))); } return(prop); }