Thank You Emmanuel, just to precise your answer,
You must change the value of
<WHERE IS YOUR JBOSS>\ server\default\deploy\ejb3.deployer\META-INF\ persistence.properties
And that fixes the problem of duplicated method.
The same problem happens for plain-Hibernate users (har archives) without ejb3 support. I see the Hibernate MBean does not support this hibernate.bytecode.provider attribute. Is there a way to define this system propertu for hibernate inside jboss without needing to change my application of the jboss start-up scripts?
I tried to add the setting "hibernate.bytecode.provider=cglib " in hibernate.properties. The setting was loaded by hibernate but javassist was still used.
Since you do not have ej3 support maybe just adding that property in hibernate.properties may work for you.
The Hibernate MBean from forces the use of javaassit, and it does not have a corresponding attribute.
(see createService() from http://fisheye.labs.jboss.com/viewrep/~raw,r=220.127.116.11/JBoss/hibernate/src/main/org/jboss/hibernate/jmx/Hibernate.java)
I understand that if I use the Hibernate MBean an hibernate.properties file will not be used.
Version 3.3 of Javassist bundled as of Hibernate 3.2.0.cr4