private void checkPostStickyEventToSubscription(Subscription newSubscription, Object stickyEvent) {
        if (stickyEvent != null) {
            // If the subscriber is trying to abort the event, it will fail (event is not tracked in posting state)
            // --> Strange corner case, which we don't take care of here.
            postToSubscription(newSubscription, stickyEvent, isMainThread());
        }
    }
Registers the given subscriber to receive events. Subscribers must call {@link #unregister(Object)} once they
are no longer interested in receiving events.
<p/>
Subscribers have event handling methods that must be annotated by {@link Subscribe}.
The {@link Subscribe} annotation also allows configuration like {@link
ThreadMode} and priority.
EventBus/src/org/greenrobot/eventbus/EventBus.java