docs: public static Map<String, Integer> getClusterSizes(
        final String projectId,
        final String instanceId
    ) throws IOException, GeneralSecurityException {
      try (BigtableClusterUtilities clusterUtil = BigtableClusterUtilities
          .forInstance(projectId, instanceId)) {
        return Collections.unmodifiableMap(
            clusterUtil.getClusters().getClustersList().stream()
                .collect(Collectors.toMap(
                        cn -> cn.getName().substring(cn.getName().indexOf("/clusters/") + 10),
                        Cluster::getServeNodes)));
      }
    }