This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
It might look like it is infinite, but both JVM Heap and object references are smart enough to allow circular references and not over create unnecessary objects. And Hibernate will only ever point to one instance of an Entity with the unique id. It will share this object with all its references, it will never create two instance of the same entity with the same id.