private boolean isClusterPresent(String dcName) {
    if (zkClientForDc.get(dcName) == null) {
      return Objects.requireNonNull(adminForDc.get(dcName), () -> "no admin for " + dcName)
          .getClusters()
          .contains(clusterName);
    } else {
      return ZKUtil.isClusterSetup(clusterName, zkClientForDc.get(dcName));
    }
  }
@param dcName the datacenter to check in.
@return true if the cluster is present and set up in this datacenter.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/HelixBootstrapUpgradeUtil.java