@VisibleForTesting
  WorkerIdentity get(String key, int index) {
    NavigableMap<Integer, WorkerIdentity> map = mActiveNodesByConsistentHashing;
    Preconditions.checkState(map != null, "Hash provider is not properly initialized");
    return get(map, key, index);
  }
@Test
  public void uninitializedThrowsException() {
    ConsistentHashProvider provider = new ConsistentHashProvider(
        1, WORKER_LIST_TTL_MS, NUM_VIRTUAL_NODES);
    assertThrows(IllegalStateException.class, () -> provider.get(OBJECT_KEY, 0));
  }