1) Handle missing methods and implementation changes in core code.
- In ZKWatcher.java, variable znodePaths has now been made private from public (See
HBASE-19761). Currently the script directly tries to reference znodePaths which will result in exception.
- Also, joinZNode method is moved to ZNodePaths and removed from ZKUtil (See
HBASE-19200). The script relies on non-existant ZKUtil.joinZNode().
2) Close zk watcher while list draining servers: The list functionality does not close the zkw instance.