code: public synchronized void registerLastTxId(String address,
        ZookeeperTxId lastTxid)
        throws IOException {
      String node = getLastTxIdNode(address);
      zkCreateRecursively(node, lastTxid.toBytes(), true, lastTxid.toString());
    }
docs: Creates a node in zookeeper denoting the current session id and the last
  transaction id processed by the primary avatarnode. This is used by the
  primary avatarnode when it shuts down cleanly.
  
  @param address
  the address of the cluster, used to create the path name for the
  znode
  @param lastTxid
  the last transaction id in the primary avatarnode
  @throws IOException