This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Returning true in isSingleton() will not magically make your bean a singleton. You have to make it work like a singleton, so you have to make sure that getObject() always returns the same object (a reference that can be cached). Is there any special reason why you are using this interface ?