private DataNodeConfig getDataNodeConfig(DataNodeConfigSource dataNodeConfigSource, String host) {
    if(dataNodeConfigSource.get(ClusterMapUtils.getInstanceName(host, PORT)) != null) {
      return dataNodeConfigSource.get(ClusterMapUtils.getInstanceName(host, PORT));
    }
    String instanceName = ClusterMapUtils.getInstanceName(host, PORT);
    return new DataNodeConfig(instanceName, host, PORT, DC, PORT + 1, PORT + 2, "rack", ClusterMapUtils.DEFAULT_XID);
  }
Case when no instance is down and all instances are present in ideal state or external view
@param helixManager
@param dataNodeConfigSource
@return
ambry-clustermap/src/test/java/com/github/ambry/clustermap/PropertyStoreCleanUpTaskTest.java