[jar2ml] GoogleApiClientBuilder.AddApi(Api, Object) throws Java.Lang.NoSuchMethodError Exception

Fixes https://bugzilla.xamarin.com/show_bug.cgi?id=22155

Jar2Xml was not emitting generic type contraints in a
format that would work with generator. It was including
nested types with a $ rather than a .

This commit fixes the output of those types to use
the correct seperator.