state.remove(d, tx);
state.acknowledge(d, tx);
   public void acknowledge(Delivery d, Transaction tx)   {      if (tx == null)      {         // acknowledge non transactionally         acknowledgeNoTx(d);         return;      }      if (log.isTraceEnabled()){ log.trace("acknowledge " + d + (tx == null ? " non-transactionally" : " transactionally in " + tx)); }      try      {         state.remove(d, tx);               }      catch (Throwable t)      {         log.error("Failed to remove delivery " + d + " from state", t);      }   }