if (numEdges == 0) {
      return false; // An edge-free graph is acyclic by definition.
    }
    if (!graph.isDirected() && numEdges >= graph.nodes().size()) {
      return true; // Optimization for the undirected case: at least one cycle must exist.
    }

    Map<Object, NodeVisitState> visitedNodes =
        Maps.newHashMapWithExpectedSize(graph.nodes().size());
    for (N node : graph.nodes()) {

     *
     * We could consider recognizing specific other collections as safe (like ImmutableCollection,
     * except ContiguousSet!) or as not worth this optimization (CopyOnWriteArrayList?).
     */
    if (parts instanceof List) {
      int size = ((List<?>) parts).size();
      if (size == 0) {
        return "";
      }

   */
  public String join(Iterable<?> parts) {
    // We don't use the same optimization here as in the JRE flavor.
    // TODO: b/381289911 - Evaluate the performance impact of doing so.
    return join(parts.iterator());
  }

  /*
   * TODO: b/381289911 - Make the Iterator overload use StringJoiner (including Android or not)—or
   * some other optimization, given that StringJoiner can over-allocate:

    @RetainedLocalRef ListenableFuture<? extends V> delegate = delegateRef;
    maybePropagateCancellationTo(delegate);

    @RetainedLocalRef Future<?> localTimer = timer;
    // Try to cancel the timer as an optimization.
    // timer may be null if this call to run was by the timer task since there is no happens-before
    // edge between the assignment to timer and an execution of the timer task.
    if (localTimer != null) {

 * inputs' {@link Comparable#compareTo compareTo} and {@link Comparator#compare compare} methods as
 * soon as one of them returns a nonzero result. This optimization is typically important only in
 * the presence of expensive {@code compareTo} and {@code compare} implementations.
 *
 * <p>See the Guava User Guide article on <a href=

       * crashes on Android when running in 32-bit mode. For maximum safety, we shouldn't use
       * Unsafe.getLong() at all, but the performance benefit on x86_64 is too great to ignore, so
       * as a compromise, we enable the optimization only on platforms that we specifically know to
       * work.
       *
       * In the future, the use of Unsafe.getLong() should be replaced by ByteBuffer.getLong(),

 * may cause corruption or runtime errors if not. It may however be shared amongst multiple OkHttpClient
 * instances.
 *
 * ## Cache Optimization
 *
 * To measure cache effectiveness, this class tracks three statistics:
 *
 *  * **[Request Count:][requestCount]** the number of HTTP requests issued since this cache was
 *    created.

    }
    Iterator<E> iterator = iterable.iterator();
    if (!iterator.hasNext()) {
      return Optional.absent();
    }

    /*
     * TODO(kevinb): consider whether this "optimization" is worthwhile. Users with SortedSets tend
     * to know they are SortedSets and probably would not call this method.
     */
    if (iterable instanceof SortedSet) {

    }
    Iterator<E> iterator = iterable.iterator();
    if (!iterator.hasNext()) {
      return Optional.absent();
    }

    /*
     * TODO(kevinb): consider whether this "optimization" is worthwhile. Users with SortedSets tend
     * to know they are SortedSets and probably would not call this method.
     */
    if (iterable instanceof SortedSet) {

      return checkNotNull(otherConverter, "otherConverter");
    }

    /*
     * We *could* override convertAll() to return its input, but it's a rather pointless
     * optimization and opened up a weird type-safety problem.
     */

    @Override
    public String toString() {
      return "Converter.identity()";
    }

    private Object readResolve() {