URLResponse from Restcontroller with Hibernate circular relationships

I  am using cocoon RestController to present my Hibernate Mysql data in 
pdf files.
The Hibernate structure has cirular relationships, so when I give the 
structure to the URLResponse there are endless StringBuilder calls.Do 
you have an idea how to solve this problem.One idea would be to present 
the data in an non Hibernate bean without cicular relationships. But may 
be there is an opportunity to avoid new beans.