RemoveDeliveryTask task = (RemoveDeliveryTask)txToRemoveDeliveryTasks.get(tx); if (task == null)
RemoveDeliveryCallback callback = (RemoveDeliveryCallback)txToRemoveDeliveryTasks.get(tx); if (callback == null)
   protected RemoveDeliveryTask addRemoveDeliveryTask(Transaction tx)   {      //TODO we could avoid this lookup by letting the tx object store the RemoveDeliveryTask      RemoveDeliveryTask task = (RemoveDeliveryTask)txToRemoveDeliveryTasks.get(tx);      if (task == null)      {         task = new RemoveDeliveryTask(tx);         txToRemoveDeliveryTasks.put(tx, task);         tx.addPostCommitTask(task);      }      return task;   }