This is more a Bukkit report but there is no tracker for it (or i haven't found it)
The methode getHandlers() in the Event.jar in Bukkit is never called. But if you want to create a custom event you have to create a new methode called getHandlerList() that is not in the Event.jar. I would recommend to make the gethandlers() methode not abstract and add a new abstract methode called getHandlerList(). I just came across this after I spend days trying to find this mistake in my code. Without looking on tutorials you would think that the abstract methode is sufficent. This was realy anoying and i think it should be changed.