Custom Binding Using EventArgs Attribute

I'm in the process of binding a 3rd party library and am not having any luck using the "EventArgs" attribute to generate the correct class or place the event handler on the owner object. I'm following the example from the Binding Types Reference and it seems to be ignoring that attribute. The type I am binding is as follows:

[Model, BaseType (typeof (NSObject))]
public interface FYXVisitDelegate {

    [Export ("didArrive:"), EventArgs ("DidArrive")]
    void  DidArrive (FYXVisit visit);

    [Export ("receivedSighting:updateTime:RSSI:"), EventArgs ("ReceivedSighting")]
    void ReceivedSighting (FYXVisit visit, NSDate updateTime, NSNumber RSSI);

    [Export ("didDepart:"), EventArgs("DidDepart")]
    void  DidDepart (FYXVisit visit);
}

I would expect there to be a DidArriveEventArgs class generated and a DidArrive event on the FYXVisitManager which has this class defined as its delegate.

Am I missing something here?