public static <E> ImmutableSet<E> of() {
    return (ImmutableSet<E>) RegularImmutableSet.EMPTY;
  }

  /**
   * Returns an immutable set containing {@code element}. Preferred over {@link
   * Collections#singleton} for code consistency, {@code null} rejection, and because the return
   * type conveys the immutability guarantee.
   */
  public static <E> ImmutableSet<E> of(E element) {

  public static <E> ImmutableSet<E> of() {
    return (ImmutableSet<E>) RegularImmutableSet.EMPTY;
  }

  /**
   * Returns an immutable set containing {@code element}. Preferred over {@link
   * Collections#singleton} for code consistency, {@code null} rejection, and because the return
   * type conveys the immutability guarantee.
   */
  public static <E> ImmutableSet<E> of(E element) {

    new EqualsTester()
        .addEqualityGroup(ImmutableSet.of(), ImmutableSet.of())
        .addEqualityGroup(ImmutableSet.of(1), ImmutableSet.of(1), ImmutableSet.of(1, 1))
        .addEqualityGroup(ImmutableSet.of(1, 2, 1), ImmutableSet.of(2, 1, 1))
        .testEquals();
  }

  /**
   * The maximum allowed probability of falsely detecting a hash flooding attack if the input is
   * randomly generated.
   */

        .addEqualityGroup(ImmutableSet.of(1), ImmutableSet.of(1), ImmutableSet.of(1, 1))
        .addEqualityGroup(ImmutableSet.of(1, 2, 1), ImmutableSet.of(2, 1, 1))
        .testEquals();
  }

  @GwtIncompatible("internals")
  public void testControlsArraySize() {
    ImmutableSet.Builder<String> builder = new ImmutableSet.Builder<String>();
    for (int i = 0; i < 10; i++) {
      builder.add("foo");

  static final Iterable<Double> ALL_DOUBLE_CANDIDATES;
  static final Iterable<Double> DOUBLE_CANDIDATES_EXCEPT_NAN;

  static {
    ImmutableSet.Builder<Double> integralBuilder = ImmutableSet.builder();
    ImmutableSet.Builder<Double> fractionalBuilder = ImmutableSet.builder();
    integralBuilder.addAll(Doubles.asList(0.0, -0.0, Double.MAX_VALUE, -Double.MAX_VALUE));
    // Add small multiples of MIN_VALUE and MIN_NORMAL

  private static final ImmutableSet<String> PS_NOT_RS =
      ImmutableSet.of("blogspot.com", "blogspot.co.uk", "uk.com");

  private static final ImmutableSet<String> PS =
      ImmutableSet.<String>builder().addAll(RS).addAll(PS_NOT_RS).build();

  private static final ImmutableSet<String> NO_PS =
      ImmutableSet.of("www", "foo.ihopethiswillneverbeapublicsuffix", "x.y.z");

  /**

     * ImmutableSet.copyOf won't short-circuit because it won't see an ImmutableSet input.
     */
    ImmutableList<ImmutableSet<String>> distinctCandidatesByAscendingSize =
        ImmutableList.of(
            ImmutableSet.of(),
            ImmutableSet.of("a"),
            ImmutableSet.of("b", "a"),
            ImmutableSet.of("c", "b", "a"),

     * ImmutableSet.copyOf won't short-circuit because it won't see an ImmutableSet input.
     */
    ImmutableList<ImmutableSet<String>> distinctCandidatesByAscendingSize =
        ImmutableList.of(
            ImmutableSet.of(),
            ImmutableSet.of("a"),
            ImmutableSet.of("b", "a"),
            ImmutableSet.of("c", "b", "a"),

  }

  private transient @Nullable ImmutableSet<Entry<K, V>> cachedEntrySet = null;

  public final ImmutableSet<Entry<K, V>> entrySet() {
    if (cachedEntrySet != null) {
      return cachedEntrySet;
    }
    return cachedEntrySet = createEntrySet();
  }

  abstract ImmutableSet<Entry<K, V>> createEntrySet();

  private transient @Nullable ImmutableSet<K> cachedKeySet = null;

        .withKeyStrengths(ImmutableSet.of(Strength.STRONG, Strength.WEAK))
        .withValueStrengths(ImmutableSet.copyOf(Strength.values()))
        .withConcurrencyLevels(ImmutableSet.of(1, 4, 16, 64))
        .withMaximumSizes(ImmutableSet.of(0, 1, 10, 100, 1000))
        .withInitialCapacities(ImmutableSet.of(0, 1, 10, 100, 1000))
        .withExpireAfterWrites(
            ImmutableSet.of(