static Map<Class<?>, Set<EventHandler>> findAllSubscribers(Object listener) {
    Class<?> listenerClass = listener.getClass();
    Map<Class<?>, Set<EventHandler>> handlersInMethod = new HashMap<Class<?>, Set<EventHandler>>();

    Map<Class<?>, Set<Method>> methods = SUBSCRIBERS_CACHE.get(listenerClass);
    if (null == methods) {
      methods = new HashMap<Class<?>, Set<Method>>();
      loadAnnotatedSubscriberMethods(listenerClass, methods);
    }
    if (!methods.isEmpty()) {
      for (Map.Entry<Class<?>, Set<Method>> e : methods.entrySet()) {
        Set<EventHandler> handlers = new HashSet<EventHandler>();
        for (Method m : e.getValue()) {
          handlers.add(new EventHandler(listener, m));
        }
        handlersInMethod.put(e.getKey(), handlers);
      }
    }

    return handlersInMethod;
  }
This implementation finds all methods marked with a {@link Subscribe} annotation.
otto/src/main/java/com/squareup/otto/AnnotatedHandlerFinder.java