I'm writing a new ES module for exposing some perf data and thought I could
easily just add a ClusterStateListener and determine from that what the
'health' of the cluster is, but I can't find the best way to do this because
the ClusterState object doesn't expose from what I can tell what the health
is. Plenty of other stuff I can export, but thought the Health value should
be simple.. ?
i'm sure I'm going blind here.