Antonio,
You needed to set it up because you used the version of GF that does not have automatic support for EclipseLink. Both, V2.1 (aka 9.1.1) and V3 will do it for you.
Regards,
-marina
[Message sent by forum member 'mvatkina' (mvatkina)]
http://forums.java.net/jive/thread.jspa?messageID=336885