private static Set<Address> collectKnownRegionServers(final ClusterMetrics clusterMetrics) {
    final Set<Address> regionServers = clusterMetrics.getLiveServerMetrics().keySet().stream()
      .map(ServerName::getAddress).collect(Collectors.toSet());
    clusterMetrics.getDeadServerNames().stream().map(ServerName::getAddress)
      .forEach(regionServers::add);
    return Collections.unmodifiableSet(regionServers);
  }
Build a set of all the host:port pairs of region servers known to this cluster.
hbase-it/src/test/java/org/apache/hadoop/hbase/chaos/actions/DumpClusterStatusAction.java