return CartesianSet.create(sets);
  }

  /**
   * Returns every possible list that can be formed by choosing one element from each of the given
   * sets in order; the "n-ary <a href="http://en.wikipedia.org/wiki/Cartesian_product">Cartesian
   * product</a>" of the sets. For example:
   *
   * <pre>{@code
   * Sets.cartesianProduct(

    checkHashCode(Sets.cartesianProduct(set(num), mt));
    checkHashCode(Sets.cartesianProduct(set(num), set(1)));
    checkHashCode(Sets.cartesianProduct(set(1), set(2, num)));
    checkHashCode(Sets.cartesianProduct(set(1, num), set(2, num - 1)));
    checkHashCode(Sets.cartesianProduct(set(1, num), set(2, num - 1), set(3, num + 1)));

    // a bigger one
    checkHashCode(

 *   <li>{@code refreshAfterWrite=[duration]}: sets {@link CacheBuilder#refreshAfterWrite}.
 *   <li>{@code weakKeys}: sets {@link CacheBuilder#weakKeys}.
 *   <li>{@code softValues}: sets {@link CacheBuilder#softValues}.
 *   <li>{@code weakValues}: sets {@link CacheBuilder#weakValues}.
 *   <li>{@code recordStats}: sets {@link CacheBuilder#recordStats}.
 * </ul>
 *

  @Override
  NavigableSet<Integer> createUnfiltered(Iterable<Integer> contents) {
    return Sets.newTreeSet(contents);
  }

  @Override
  NavigableSet<Integer> filter(
      NavigableSet<Integer> elements, Predicate<? super Integer> predicate) {
    return Sets.filter(elements, predicate);
  }

  // the CacheBuilder default).
  private Set<Integer> concurrencyLevels = Sets.newHashSet((Integer) null);
  private Set<Integer> initialCapacities = Sets.newHashSet((Integer) null);
  private Set<Integer> maximumSizes = Sets.newHashSet((Integer) null);
  private Set<DurationSpec> expireAfterWrites = Sets.newHashSet((DurationSpec) null);
  private Set<DurationSpec> expireAfterAccesses = Sets.newHashSet((DurationSpec) null);

    assertEquals("[" + JOINER.join(map.keySet()) + "]", map.keySet().toString());
    assertEquals("[" + JOINER.join(map.values()) + "]", map.values().toString());

    assertEquals(Sets.newHashSet(map.entrySet()), map.entrySet());
    assertEquals(Sets.newHashSet(map.keySet()), map.keySet());
  }

    Set<String> set = of("a", "b");
    assertEquals(Sets.newHashSet("a", "b"), set);
  }

  public void testCreation_threeElements() {
    Set<String> set = of("a", "b", "c");
    assertEquals(Sets.newHashSet("a", "b", "c"), set);
  }

  public void testCreation_fourElements() {
    Set<String> set = of("a", "b", "c", "d");
    assertEquals(Sets.newHashSet("a", "b", "c", "d"), set);
  }

    Set<String> set = of("a", "b");
    assertEquals(Sets.newHashSet("a", "b"), set);
  }

  public void testCreation_threeElements() {
    Set<String> set = of("a", "b", "c");
    assertEquals(Sets.newHashSet("a", "b", "c"), set);
  }

  public void testCreation_fourElements() {
    Set<String> set = of("a", "b", "c", "d");
    assertEquals(Sets.newHashSet("a", "b", "c", "d"), set);
  }

  @SuppressWarnings("GoodTime")
  long getAccessTime();

  /** Sets the entry access time in ns. */
  @SuppressWarnings("GoodTime") // b/122668874
  void setAccessTime(long time);

  /** Returns the next entry in the access queue. */
  ReferenceEntry<K, V> getNextInAccessQueue();

  /** Sets the next entry in the access queue. */
  void setNextInAccessQueue(ReferenceEntry<K, V> next);

    assertEquals("google", keySet.last());
    assertEquals(StringLength.COMPARATOR, keySet.comparator());
    assertEquals(Sets.<@Nullable String>newHashSet(null, "tree"), keySet.headSet("yahoo"));
    assertEquals(Sets.newHashSet("google"), keySet.tailSet("yahoo"));
    assertEquals(Sets.newHashSet("tree"), keySet.subSet("ask", "yahoo"));
  }

  @GwtIncompatible // SerializableTester