Which book or study guide are you referring? Design patterns are topics in the Java EE 5 WCD exam. From the Java EE 6 exam, IMO the objectives talks about MVC this and that. So MVC itself is a design pattern. Apart from that, from the objectives no other patterns.
The trick here is to do a search on the Certification Results forum as you might find an answer from the people who have passed the EE6 exam. I did a quick search and I found this thread with a clear answer to your question.