Zookeeper client leaks file descriptor in case of UnresolvedAddressException

Zookeeper client is causing the file descriptor leak when it is unable to properly reach the destination. In this case, the DNS lookup fails but still leaves an unbounded TCP socket.

A colleague took a heap dump of the application. Saw 17400 sun.nio.ch.SocketChannelImpl object reachable from root and the number matched the open file descriptors on the host.

More analysis from the heap dump in the comment.