You're not posting a distributed notification, or using a distributed notification center. This means you know that the notification came from the current application.
Meanwhile, you're generating the notifications yourself, so if you did need to know the application, you could just add that in.
Finally, the events you're embedding are global key events, which do not have an associated application. Except in special cases, they're not generated by any application, they're generated by the user typing on the keyboard.