1. Deploy a ZooKeeper cluster with one node.
2. Create a Ephemeral znode.
3. Change the system time of the ZooKeeper node to a earlier point.
4. Disconnect the client with the ZooKeeper server.
Then the ephemeral znode will exist for a long time even when session timeout.
I have read the ZooKeeper source code and I find the code int SessionTrackerImpl.java，
I think it may be better to use System.nanoTime(), not System.currentTimeMillis, because the later can be changed manually or automatically by a NTP client.