public void addHosts(Collection<String> hosts) {
    synchronized (hostNames) {
      for (String host : hosts) {
        addHost(host);
      }
    }
  }
Associate multiple host names to the host group.

@param hosts  collection of host names to associate with the host group
ambari-server/src/main/java/org/apache/ambari/server/topology/HostGroupInfo.java