HIbernate 3.5 issue with Weblogic 12c and Java8

Hi Every one,
We are having a legacy application which was running fine with following
Weblogic 12.1.3.0
Hibernate 3.5
Java7
Now with a compulsary upgrade of weblogic and Java to
Weblogic 12.2.1.4
Java8
HIbernate 3.5 (we cannot upgrade this now as it will increase the complexity)

we are getting below exception. There is no change in any config file only change is with Weblogic and Java version.

org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer]
at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:110)
at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:135)
at org.hibernate.tuple.entity.EntityEntityModeToTuplizerMapping.(EntityEntityModeToTuplizerMapping.java:80)
at org.hibernate.tuple.entity.EntityMetamodel.(EntityMetamodel.java:323)
at org.hibernate.persister.entity.AbstractEntityPersister.(AbstractEntityPersister.java:475)
at org.hibernate.persister.entity.SingleTableEntityPersister.(SingleTableEntityPersister.java:133)
at org.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:84)
at org.hibernate.impl.SessionFactoryImpl.(SessionFactoryImpl.java:295)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1385)
at x.x.x.x.hibernate.HibernateUtil.(HibernateUtil.java:110)
at x.x.x.x.x.x.x.x.x(x.java:83)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.jamonapi.proxy.MonProxy.invoke(MonProxy.java:69)
at com.sun.proxy.$Proxy296.getComponentsRunningState(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedConstructorAccessor148.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:107)
… 20 more
Caused by: java.lang.IllegalStateException: Unable to load cache item
at net.sf.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:79)
at net.sf.cglib.core.internal.LoadingCache.get(LoadingCache.java:34)
at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:116)
at net.sf.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:291)
at net.sf.cglib.proxy.Enhancer.createHelper(Enhancer.java:480)
at net.sf.cglib.proxy.Enhancer.createClass(Enhancer.java:337)
at org.hibernate.proxy.pojo.cglib.CGLIBLazyInitializer.getProxyFactory(CGLIBLazyInitializer.java:150)
at org.hibernate.proxy.pojo.cglib.CGLIBProxyFactory.postInstantiate(CGLIBProxyFactory.java:66)
at org.hibernate.tuple.entity.PojoEntityTuplizer.buildProxyFactory(PojoEntityTuplizer.java:187)
at org.hibernate.tuple.entity.AbstractEntityTuplizer.(AbstractEntityTuplizer.java:170)
at org.hibernate.tuple.entity.PojoEntityTuplizer.(PojoEntityTuplizer.java:77)
… 24 more
Caused by: java.lang.ExceptionInInitializerError
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at x.x.x.x.x.PortfolioContractCode$$EnhancerByCGLIB$$6c5e29e5.CGLIB$STATICHOOK106()
at x.x.x.x.x.PortfolioContractCode$$EnhancerByCGLIB$$6c5e29e5.()
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at net.sf.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:467)
at net.sf.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:336)
at net.sf.cglib.proxy.Enhancer.generate(Enhancer.java:492)
at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:93)
at net.sf.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:91)
at net.sf.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at net.sf.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61)
… 34 more
Caused by: java.lang.NullPointerException
at x.x.x.x.x.HibernateUtil.currentSession(HibernateUtil.java:190)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.jamonapi.proxy.MonProxy.invoke(MonProxy.java:69)
at com.sun.proxy.$Proxy270.getCodetable(Unknown Source)
… 48 more
Does this implies that there is some compatibility issue between hibernate, weblogic and java? Or there is some other things missing?
I have already tried adding javassist.jar in our war file, but it did not work.