private static void loadAnnotatedSubscriberMethods(Class<?> listenerClass,
      Map<Class<?>, Set<Method>> subscriberMethods) {
    Map<Class<?>, Method> producerMethods = new HashMap<Class<?>, Method>();
    loadAnnotatedMethods(listenerClass, producerMethods, subscriberMethods);
  }
Cache event bus subscriber methods for each class.
otto/src/main/java/com/squareup/otto/AnnotatedHandlerFinder.java