I'm not sure I like the idea of exposing details of server configuration through the public API when it isn't needed for client operations. I'm not sure client code should have any knowledge that any monitor services even exist.
At the very least, I'm concerned about this being a part of the public API. What if we replace the monitor with better monitoring solutions? What if the user isn't running a monitor? What if it is running multiple monitors? Would a utility class be better suited to this? Or maybe just put it in HdfsZooInstance rather than Instance itself? Will adding it to the Instance interface disrupt the API in undesirable ways?
Is there a precedent for exposing a monitoring service within the service being monitored? It seems a bit awkward for a service to assume it's being monitored at all, never mind that it's monitored with a very specific type of monitoring tool (in this case, one that has a location attribute that it shares with the services it is monitoring).