public static HostsType highAvailability(String master, String secondary, LinkedHashSet<String> hosts) {
    return new HostsType(singletonList(new HighAvailabilityHosts(master, singletonList(secondary))), hosts);
  }
Create an instance with exactly one high availability host (master-secondary pair) and with the given host set
ambari-server/src/main/java/org/apache/ambari/server/stack/HostsType.java