Implement a thread-safe EventManager class that handles event notifications asynchronously to multiple listeners. The EventManager should be able to register listeners, deregister them, and notify them of events in a concurrent environment.

• There is already defined an EventListener interface with a single method onEvent(Event e). This method is called whenever an event is notified.
• There is already defined an Event class that encapsulates details of an event, such as type and source.

Implement an EventManager class with the following capabilities:

• Listener registration: Method registerListener(EventListener listener) to add a new listener.
• Listener deregistration: Method deregisterListener(EventListener listener) to remove an existing listener.
• Event notification: Method notifyEvent(Event event) to asynchronously notify all registered listeners of an event.
• Shutdown mechanism: Method shutdown() to properly close any resources if required.