Interface describing a mechanism that connects Event Bus clusters. The terminal is responsible for delivering
published Events with all of the clusters available in the Event Bus (either locally, or remotely).
Terminals are typically bound to a single Event Bus instance, but may be aware that multiple instances exist in
order to form a bridge between these Event Buses.
Invoked when an Event Listener has been assigned to a cluster that was not yet known to the Event Bus. This
method is invoked only once for each cluster that was assigned an Event Listener. Subsequent Event Listeners
are added to the cluster. Cluster remain "live" when all event listeners have been removed from them.