@Override
  public DataNodeConfig get(String instanceName) {
    InstanceConfig instanceConfig = helixAdmin.get().getInstanceConfig(clusterName, instanceName);
    return instanceConfig != null ? converter.convert(instanceConfig) : null;
  }
@param helixManager the {@link HelixManager} to use as the source of truth for {@link InstanceConfig}s.
@param clusterMapConfig the {@link ClusterMapConfig} to use.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/InstanceConfigToDataNodeConfigAdapter.java