code: public void register(Object subscriber) {
          Class<?> subscriberClass = subscriber.getClass();
          List<SubscriberMethod> subscriberMethods = subscriberMethodFinder.findSubscriberMethods(subscriberClass);
          synchronized (this) {
              for (SubscriberMethod subscriberMethod : subscriberMethods) {
                  subscribe(subscriber, subscriberMethod);
              }
          }
      }
docs: 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.