default Collection<ServerName> getRegionServers(boolean excludeDecommissionedRS)
    throws IOException {
    List<ServerName> allServers =
      getClusterMetrics(EnumSet.of(Option.SERVERS_NAME)).getServersName();
    if (!excludeDecommissionedRS) {
      return allServers;
    }
    List<ServerName> decommissionedRegionServers = listDecommissionedRegionServers();
    return allServers.stream().filter(s -> !decommissionedRegionServers.contains(s))
      .collect(ImmutableList.toImmutableList());
  }
Retrieve all current live region servers including decommissioned if excludeDecommissionedRS is
false, else non-decommissioned ones only
@param excludeDecommissionedRS should we exclude decommissioned RS nodes
@return all current live region servers including/excluding decommissioned hosts
@throws IOException if a remote or network exception occurs
hbase-client/src/main/java/org/apache/hadoop/hbase/client/Admin.java