code: public final void persistLock(final Transaction transaction) throws ProtocolException, TransactionException, SevereMessageStoreException
      {
          Membership membership = _getMembership();
          if (null == membership)
          {
              throw new NotInMessageStore();
          }
          membership.persistLock(transaction);
      }
docs: Use this method to persist the lock currently active on the item.
  Item MUST be locked.
  
  @param transaction
  @throws SevereMessageStoreException
  @throws {@ProtocolException} Thrown if an add is attempted when the
  transaction cannot allow any further work to be added i.e. after
  completion of the transaction.
  
  @throws {@TransactionException} Thrown if an unexpected error occurs.