}
  }

  /**
   * Returns the identity function.
   *
   * <p><b>Discouraged:</b> Prefer using a lambda like {@code v -> v}, which is shorter and often
   * more readable.
   */
  // implementation is "fully variant"; E has become a "pass-through" type
  @SuppressWarnings("unchecked")
  public static <E extends @Nullable Object> Function<E, E> identity() {
    return (Function<E, E>) IdentityFunction.INSTANCE;
  }

    }
  }

  public void testTransform_rejectionPropagatesToOutput() throws Exception {
    SettableFuture<Foo> input = SettableFuture.create();
    Function<Foo, Foo> identity = identity();
    ListenableFuture<Foo> transformed = transform(input, identity, REJECTING_EXECUTOR);
    input.set(new Foo());
    try {
      getDone(transformed);
      fail();
    } catch (ExecutionException expected) {

   * Arrays#hashCode(Object[])}. Note that array arguments to this method, with the exception of a
   * single Object array, do not get any special handling; their hash codes are based on identity
   * and not contents.
   *
   * <p>This is useful for implementing {@link Object#hashCode()}. For example, in an object that
   * has three properties, {@code x}, {@code y}, and {@code z}, one could write:
   *

   * other Unicode encodings can).
   *
   * <p><b>Note:</b> This escaper only performs minimal escaping to make content structurally
   * compatible with HTML. Specifically, it does not perform entity replacement (symbolic or
   * numeric), so it does not replace non-ASCII code points with character references. This escaper
   * escapes only the following five ASCII characters: {@code '"&<>}.
   */

 *
 * <p><b>Note:</b> Currently the escapers provided by this class do not escape any characters
 * outside the ASCII character range. Unlike HTML escaping the XML escapers will not escape
 * non-ASCII characters to their numeric entity replacements. These XML escapers provide the minimal
 * level of escaping to ensure that the output can be safely included in a Unicode XML document.
 *
 * <p>For details on the behavior of the escapers in this class, see sections <a

  public void testSerialization() {
    assertEquals(Integer.valueOf(5), reserialize(Suppliers.ofInstance(5)).get());
    assertEquals(
        Integer.valueOf(5),
        reserialize(Suppliers.compose(Functions.identity(), Suppliers.ofInstance(5))).get());
    assertEquals(Integer.valueOf(5), reserialize(Suppliers.memoize(Suppliers.ofInstance(5))).get());
    assertEquals(
        Integer.valueOf(5),

  public void testSerialization() {
    assertEquals(Integer.valueOf(5), reserialize(Suppliers.ofInstance(5)).get());
    assertEquals(
        Integer.valueOf(5),
        reserialize(Suppliers.compose(Functions.identity(), Suppliers.ofInstance(5))).get());
    assertEquals(Integer.valueOf(5), reserialize(Suppliers.memoize(Suppliers.ofInstance(5))).get());
    assertEquals(
        Integer.valueOf(5),

   * example, {@code [] < [1] < [1, 2] < [2] < [1 << 31]}.
   *
   * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
   * support only identity equality), but it is consistent with {@link Arrays#equals(int[], int[])}.
   */
  public static Comparator<int[]> lexicographicalComparator() {
    return LexicographicalComparator.INSTANCE;
  }

   * @since 27.1
   */
  @CheckForNull
  V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue);

  //
  // ValueGraph identity
  //

  /**
   * Returns {@code true} iff {@code object} is a {@link ValueGraph} that has the same elements and
   * the same structural relationships as those in this graph.
   *

   * unsigned.
   *
   * <p>The returned comparator is inconsistent with {@link Object#equals(Object)} (since arrays
   * support only identity equality), but it is consistent with {@link
   * java.util.Arrays#equals(byte[], byte[])}.
   *
   * @since 2.0
   */
  public static Comparator<byte[]> lexicographicalComparator() {