assertEquals(false, Defaults.defaultValue(boolean.class).booleanValue());
    assertEquals('\0', Defaults.defaultValue(char.class).charValue());
    assertEquals(0, Defaults.defaultValue(byte.class).byteValue());
    assertEquals(0, Defaults.defaultValue(short.class).shortValue());
    assertEquals(0, Defaults.defaultValue(int.class).intValue());
    assertEquals(0, Defaults.defaultValue(long.class).longValue());

   * Returns the first element in {@code iterable} that satisfies the given predicate, or {@code
   * defaultValue} if none found. Note that this can usually be handled more naturally using {@code
   * tryFind(iterable, predicate).or(defaultValue)}.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code
   * stream.filter(predicate).findFirst().orElse(defaultValue)}
   *
   * @since 7.0
   */
  // The signature we really want here is...
  //

   * @return function that returns {@code map.get(a)} when {@code a} is a key, or {@code
   *     defaultValue} otherwise
   */
  public static <K extends @Nullable Object, V extends @Nullable Object> Function<K, V> forMap(
      Map<K, ? extends V> map, @ParametricNullness V defaultValue) {
    return new ForMapWithDefault<>(map, defaultValue);
  }

    return false;
  }

  @Override
  public T get() {
    throw new IllegalStateException("Optional.get() cannot be called on an absent value");
  }

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

  @SuppressWarnings("unchecked") // safe covariant cast
  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {

    return false;
  }

  @Override
  public T get() {
    throw new IllegalStateException("Optional.get() cannot be called on an absent value");
  }

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

  @SuppressWarnings("unchecked") // safe covariant cast
  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {

   * @return function that returns {@code map.get(a)} when {@code a} is a key, or {@code
   *     defaultValue} otherwise
   */
  public static <K extends @Nullable Object, V extends @Nullable Object> Function<K, V> forMap(
      Map<K, ? extends V> map, @ParametricNullness V defaultValue) {
    return new ForMapWithDefault<>(map, defaultValue);
  }

  @CheckForNull
  public V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue) {
    return delegate().edgeValueOrDefault(nodeU, nodeV, defaultValue);
  }

  @Override
  @CheckForNull
  public V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue) {
    return delegate().edgeValueOrDefault(endpoints, defaultValue);
  }

    @SuppressWarnings("unchecked") // Assume all default values are generics safe.
    T defaultValue = (T) defaultValues.getInstance(rawType);
    if (defaultValue != null) {
      return defaultValue;
    }
    @SuppressWarnings("unchecked") // ArbitraryInstances always returns generics-safe dummies.
    T value = (T) ArbitraryInstances.get(rawType);
    if (value != null) {
      return value;
    }

   * otherwise, returns {@code defaultValue}.
   *
   * <p>In an undirected graph, this is equal to {@code edgeValueOrDefault(nodeV, nodeU,
   * defaultValue)}.
   *
   * @throws IllegalArgumentException if {@code nodeU} or {@code nodeV} is not an element of this
   *     graph
   */
  @CheckForNull
  V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue);

  /**

    throw new UnsupportedOperationException();
  }

  private <T> T pickInstance(T[] instances, T defaultValue) {
    return pickInstance(Arrays.asList(instances), defaultValue);
  }

  private <T> T pickInstance(Collection<T> instances, T defaultValue) {
    if (instances.isEmpty()) {
      return defaultValue;
    }
    // generateInt() is 1-based.