code: @Deprecated
    public int getClusterSize(String clusterId, String zoneId) {
      Cluster cluster = getCluster(clusterId, zoneId);
      String message = String.format("Cluster %s/%s was not found.", clusterId, zoneId);
      Preconditions.checkNotNull(cluster, message);
      return cluster.getServeNodes();
    }
docs: Gets the serve node count of the cluster.
  @param clusterId
  @param zoneId
  @return the {@link Cluster#getServeNodes()} of the clusterId.
  @deprecated Use {@link #getCluster(String, String)} or {@link #getSingleCluster()} and then
  call {@link Cluster#getServeNodes()}.