Subclassing causes: The type has no constructors defined

[erik-kallen]

From @n9 (Saltarelle/SaltarelleCompiler#285)

I am trying to implement the Boostrap DatePicker event object:

    [Imported]
    public class BootstrapDatePickerEvent : jQueryEvent
    {
        public DateTime Date;
        public DateTime Dates;
    }

But it gives me the following error:

The type 'jQueryApi.jQueryEvent' has no constructors defined.

Why?
How to implement it?