Troubles with Wicket vs. Glassfish

Weekend is gone and here is a resultsheet of my work, study, tests, workarounds etc.
First of all - Java 6 Mustang has limited backward compatibility. I can't say more on this right now, but based on my experiments, it can't work with Java 1.3 classes. That's quite surprising ! I'll try to get more on the subject.
I didn't succeed to improve performance of the EJB with complex mapping. Persistence provider is still loading whole database with a sign of some kind of recursion when I'm trying to get just entity of one type (for example an employee). I've tried almost everything ! Bad luck though ...
All right, the next task was preparation for the certification. I've accomplished 3 chapters (out of 15 total) and my test ratio is cca. 90%. That's OK as required ratio is appriximately 60%. But what I hate about the certification test are questions like - given interface A with five methods and class B that claims to implement interface A but actually isn't implementing any method, what will be result of compilation attempt. a) the class will not be compiled b) ... c) ... d) class will be compiled but can't be instantioned e)class will be abstract. And correct answer is d) and e). But why ?! On Java 5 this example works and class is even runnable (as long as you don't call methods inherited from the interface). On JDK 4 it fails to compile at all. So what is conclusion ?!
Wicket - Wicket is excelent. So for I like it very match, but for reason unknown Wicket is in collision with Glassfish. When I deploy my Wicket application onto the Glassfish for a fiveth time Glassfish crash with strange message like "PrmGen" out of memory ... Anyway, Glassfish has a serious problem with webservices. Webservice with method that returns not elemental objects (not Strings, Lists ...) cause Glassfish to crash or if I'm lucky it just cause weird behaviour of the Glassfish ... Nobody knows why and I don't mind to find it. So I'll go to the Tomcat. Tomcat is a proven server so maybe, I'll be more lucky with this one.