static List<BigtableResourceManagerCluster> generateDefaultClusters(
      String baseString, String zone, int numNodes, StorageType storageType) {

    String clusterId =
        generateResourceId(
            baseString.toLowerCase(),
            ILLEGAL_CLUSTER_CHARS,
            REPLACE_CLUSTER_CHAR,
            MAX_CLUSTER_ID_LENGTH,
            TIME_FORMAT);
    BigtableResourceManagerCluster cluster =
        BigtableResourceManagerCluster.create(clusterId, zone, numNodes, storageType);

    return ImmutableList.of(cluster);
  }
@Test
  public void testGenerateDefaultClustersShouldThrowErrorWhenTestIdIsEmpty() {
    assertThrows(
        IllegalArgumentException.class,
        () -> generateDefaultClusters("", ZONE, NUM_NODES, STORAGE_TYPE));
  }