This was almost certainly my fault, but as I look at the implementation of Sets.cartesianProduct, I think its `contains` method made the assumption that `ImmutableSet.asList().indexOf` was O(1), which is no longer the case for Android.  It should probably get a specific `contains` implementation that actually is O(sets), not O(sets*setSize).
return Collections.newSetFromMap(Maps.<E, Boolean>newIdentityHashMap());
  }
  /**
   * Creates an empty {@code CopyOnWriteArraySet} instance.
   *
   * <p><b>Note:</b> if you need an immutable empty {@link Set}, use {@link Collections#emptySet}
   * instead.
   *
   * @return a new, empty {@code CopyOnWriteArraySet}
   * @since 12.0
   */
  @GwtIncompatible 
  public static <E> CopyOnWriteArraySet<E> newCopyOnWriteArraySet() {
    return new CopyOnWriteArraySet<E>();
  }
  /**
   * Creates a {@code CopyOnWriteArraySet} instance containing the given elements.
   *
   * @param elements the elements that the set should contain, in order
   * @return a new {@code CopyOnWriteArraySet} containing those elements
   * @since 12.0
   */
  @GwtIncompatible 
  public static <E> CopyOnWriteArraySet<E> newCopyOnWriteArraySet(Iterable<? extends E> elements) {
    
    
    Collection<? extends E> elementsCollection =
        (elements instanceof Collection)
            ? Collections2.cast(elements)
            : Lists.newArrayList(elements);