Allowing more path entries in Javascript function path for JSONP.

I followed the instructions to render JSONP (http://www.ninjaframework.org/documentation/working_with_json_jsonp.html), but I have a problem with my callback function.

When I pass ?callback=MyApp.Path.myCallback123, it does not produce:

MyApp.Path.myCallback123({'response': 'data'})

instead it produces:

onResponse({'response': 'data'})

When I pass ?callback=MyAppPath.myCallback123 (removing first '.', or second), it works fine.

In my case, I need to pass a parameter like "callback=Ext.data.JsonP.callback4". Here, I don't want to override all related classes in ExtJS, so how can I solve this problem with Ninja?