There as been a pull request[1] containing Javdoc generation using Grapviz[2]. 
I don't think it would make sense to add this to only the SimplePush Server, but instead if this is something we want it would be better to add it to all Java projects so that our docs look the same. 

An example is provided with the pull request so that you can see what it looks like. 

What do people think? 
+1 Let's add this
-1  Let's not 

[1] https://github.com/aerogear/aerogear-simplepush-server/pull/35
[2] https://code.google.com/p/apiviz/