docs: @Override
     public void commit() throws RollbackException, HeuristicMixedException,
                                 HeuristicRollbackException, SecurityException,
                                 IllegalStateException, SystemException {
        DummyTransaction tx = getTransaction();
        if (tx == null)
           throw new IllegalStateException("thread not associated with transaction");
        tx.commit();
  
        // Disassociate tx from thread.
        setTransaction(null);
     }