Why is an optional DatePicker being validated?

[Jordan]

How can we make sure optional field is not validated?  Also the model is a DateTime? type.

 

                                    i.Add()
                                        .Field(x=>x.ProductionDate)
                                        .Label(l => l.Text(Extensions.GetPropertyDisplayName<Detail_InfoForm_ViewModel>(x => x.ProductionDate)).Optional(true))
                                        .Editor(e => e.DatePicker()
                                            .HtmlAttributes(new { style = "width: 100%", title = "Production date" })
                                            .DateInput()
                                        );