exception embêtante :net.sf.cglib.core.CodeGenerationException

bonjour ,
sur mon projet jsf j'ai toujours l'exception suivante :

Code:

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net.sf.cglib.core.CodeGenerationException: java.lang.reflect.InvocationTargetException-->null
	at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:237)
	at net.sf.cglib.proxy.Enhancer.createHelper(Enhancer.java:377)
	at net.sf.cglib.proxy.Enhancer.createClass(Enhancer.java:317)
	at org.hibernate.proxy.CGLIBLazyInitializer.getProxyFactory(CGLIBLazyInitializer.java:126)
	at org.hibernate.proxy.CGLIBProxyFactory.postInstantiate(CGLIBProxyFactory.java:41)
	at org.hibernate.tuple.PojoEntityTuplizer.buildProxyFactory(PojoEntityTuplizer.java:161)
	at org.hibernate.tuple.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:131)
	at org.hibernate.tuple.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:55)
	at org.hibernate.tuple.TuplizerLookup.create(TuplizerLookup.java:64)
	at org.hibernate.tuple.EntityMetamodel.<init>(EntityMetamodel.java:257)
	at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:412)
	at org.hibernate.persister.entity.JoinedSubclassEntityPersister.<init>(JoinedSubclassEntityPersister.java:90)
	at org.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:58)
	at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:216)
	at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1176)
	at com.eca.EcaHibernateUtil.getSessionFactory(EcaHibernateUtil.java:62)
	at com.eca.foundation.persist.DataService.getSession(DataService.java:301)

si quelqu'un a une idée sur la source de problème je serrai très reconnaissant.
merci