Looking for free O/R mapping tool

[Nikolaus Rumm]

Hello,   I am looking for a free O/R mapping tool to support me in implementing my domain objects. These domain objects are simple Java objects that are wrapped by and depend on entity beans. The tool should be able to generate Oracle 8.1.5 compatible SQL. Well, it should be free as I use it as a part of my master thesis.   Any suggestions ?   Nikolaus