ASControlNode not sending action to the responder chain when target is nil ("send to first responder")

The implementation of  `- [ASControlNode addTarget:action:forControlEvents:]` doesn't store action added to a `nil` target.
I'm not familiar enough with this system to know for sure, but is this behavior correct? It looks like it propagates events with nil targets to the UIApplication, but the UIResponder docs for `addTarget:action:forControlEvents:` seem to imply that events propagate to the next responder:

`The target object—that is, the object to which the action message is sent. If this is nil, the responder chain is searched for an object willing to respond to the action message.`