}

  @Override
  public T or(Supplier<? extends T> supplier) {
    return checkNotNull(
        supplier.get(), "use Optional.orNull() instead of a Supplier that returns null");
  }

  @Override
  public @Nullable T orNull() {
    return null;
  }

  @Override
  public Set<T> asSet() {
    return Collections.emptySet();
  }

  @Override
  public <V> Optional<V> transform(Function<? super T, V> function) {

  public boolean isPresent() {
    return true;
  }

  @Override
  public T get() {
    return reference;
  }

  @Override
  public T or(T defaultValue) {
    checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
    return reference;
  }

  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {
    checkNotNull(secondChoice);
    return this;
  }

  @Override

  // If users use this when they shouldn't, we hope that NewApi will catch subsequent Optional calls
  @IgnoreJRERequirement
  public java.util.Optional<T> toJavaUtil() {
    return java.util.Optional.ofNullable(orNull());
  }

  Optional() {}

  /**
   * Returns {@code true} if this holder contains a (non-null) instance.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> no differences.
   */

  }

  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
  public void testOrNull_present() {
    assertEquals("a", Optional.of("a").orNull());
  }

  public void testOrNull_absent() {
    assertThat(Optional.absent().orNull()).isNull();
  }

  public void testAsSet_present() {
    Set<String> expected = Collections.singleton("a");
    assertEquals(expected, Optional.of("a").asSet());

   */
  @Override
  public <A extends Annotation> @Nullable A getDeclaredAnnotation(Class<A> annotationType) {
    checkNotNull(annotationType);
    return FluentIterable.from(annotations).filter(annotationType).first().orNull();
  }

  /**
   * @since 18.0
   */
  @Override
  public <A extends Annotation> A[] getDeclaredAnnotationsByType(Class<A> annotationType) {
    @Nullable A[] result =

      new Function<Optional<?>, @Nullable Object>() {
        @Override
        public @Nullable Object apply(Optional<?> optional) {
          return optional.orNull();
        }
      };

  /**
   * Sets.cartesianProduct doesn't allow sets that contain null, but we want null to mean "don't