Runnable task = (Runnable)iter.next(); task.run();
TxCallback callback = (TxCallback)iter.next(); callback.afterRollback();
   public void rollback() throws Exception   {      //TODO - rollback the tx in the database      if (log.isTraceEnabled()) { log.trace("rolling back " + this); }      state = STATE_ROLLEDBACK;            if (insertedTXRecord)      {         pm.rollbackTx(this);      }            Iterator iter = postRollbackTasks.iterator();      while (iter.hasNext())      {         Runnable task = (Runnable)iter.next();         task.run();      }   }