Event subscribing pattern in Java

I have this class EventGenerator that can generate objects of any subclass of an interface Event. I would like to allow objects to implement a method that receives a specific subclass T of Event that will be called when the generator emits a new event of that type.

I would like to follow the Open-Closed principle as much as possible, since subclasses of Event may be created in the future. I was thinking about an interface EventSubscriber<T extends Event> with a method receiveEvent(T), but how can I add and store the subscriber in the generator object?