`mntr` Metricset fetches the data returned by the `mntr` admin keyword. It exposes the following metrics:

* `zookeeper.mntr.hostname`: ZooKeeper hostname.
* `zookeeper.mntr.approximate_data_size`: Approximate size of ZooKeeper data.
* `zookeeper.mntr.latency.avg`: Average latency between ensemble hosts in milliseconds.
* `zookeeper.mntr.ephemerals_count`: Number of ephemeral znodes.
* `zookeeper.mntr.followers`: Number of followers seen by the current host.
* `zookeeper.mntr.max_file_descriptor_count`: Maximum number of file descriptors allowed for the ZooKeeper process.
* `zookeeper.mntr.latency.max`: Maximum latency in milliseconds.
* `zookeeper.mntr.latency.min`: Minimum latency in milliseconds.
* `zookeeper.mntr.num_alive_connections`: Number of connections to ZooKeeper that are currently alive.
* `zookeeper.mntr.open_file_descriptor_count`: Number of file descriptors open by the ZooKeeper process.
* `zookeeper.mntr.outstanding_requests`: Number of outstanding requests that need to be processed by the cluster.
* `zookeeper.mntr.packets.received`: Number of ZooKeeper network packets received.
* `zookeeper.mntr.packets.sent`: Number of ZooKeeper network packets sent.
* `zookeeper.mntr.pending_syncs`: Number of pending syncs to carry out to ZooKeeper ensemble followers.
* `zookeeper.mntr.server_state`: Role in the ZooKeeper ensemble.
* `zookeeper.mntr.synced_followers`: Number of synced followers reported when a node server_state is leader.
* `zookeeper.mntr.version`: Version and build string reported.
* `zookeeper.mntr.watch_count`: Number of watches currently set on the local ZooKeeper process.
* `zookeeper.mntr.znode_count`: Number of znodes reported by the local ZooKeeper process.
