java.sql.SQLException: Due to vendor limitations, setting transaction isolation for "Oracle XA" JDBC

Getting an error re: transaction isolation but i don't see it set anywhere.  Newbie to WL.  Please see details below

On WL 10.3.6/ oracle RAC/Java(TM) SE Runtime Environment (build 1.6.0_33-b04)

Getting error deployment. 

2013-10-29 01:03:24,047 ERROR [dao.ConnectionHelper] Failed to set the txn iso level to Connection.TRANSACTION_SERIALIZABLE. It remains at Connection.TRANSACTION_READ_COMMITTED []

java.sql.SQLException: Due to vendor limitations, setting transaction isolation for "Oracle XA" JDBC XA driver is not supported.
        at weblogic.jdbc.wrapper.JTAConnection.setTransactionIsolation(JTAConnection.java:492)
        at sun.reflect.GeneratedMethodAccessor965.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)