assertThat(Enums.getIfPresent(TestEnum.class, "POODLE")).hasValue(TestEnum.POODLE);

    assertThat(Enums.getIfPresent(TestEnum.class, "CHEETO")).isPresent();
    assertThat(Enums.getIfPresent(TestEnum.class, "HONDA")).isPresent();
    assertThat(Enums.getIfPresent(TestEnum.class, "POODLE")).isPresent();

    assertThat(Enums.getIfPresent(TestEnum.class, "CHEETO")).hasValue(TestEnum.CHEETO);

  Optional() {}

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

  /**
   * Returns the contained instance, which must be present. If the instance might be absent, use
   * {@link #or(Object)} or {@link #orNull} instead.
   *

        for (String selector : projectSelectors) {
            Optional<MavenProject> optSelectedProject =
                    findOptionalProjectBySelector(projects, baseDirectory, selector);
            if (!optSelectedProject.isPresent()) {
                String message = "Could not find the selected project in the reactor: " + selector;
                throw new MavenExecutionException(message, request.getPom());
            }

        if (!changed(member)) {
            return null
        }

        Optional<CtClass> oldClass = member.oldClass
        Optional<CtClass> newClass = member.newClass
        if (!oldClass.isPresent() || !newClass.isPresent()) {
            // breaking change would be reported
            return null
        }

        return checkSuperClassChanges(member, oldClass.get(), newClass.get())
    }

  }

  public void testIsPresent_no() {
    assertFalse(Optional.absent().isPresent());
  }

  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
  public void testIsPresent_yes() {
    assertTrue(Optional.of("training").isPresent());
  }

  public void testGet_absent() {
    Optional<String> optional = Optional.absent();

  @SuppressWarnings("unchecked") // implementation is "fully variant"
  static <T> Optional<T> withType() {
    return (Optional<T>) INSTANCE;
  }

  private Absent() {}

  @Override
  public boolean isPresent() {
    return false;
  }

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

  @Override
  public T or(T defaultValue) {

@GwtCompatible
@ElementTypesAreNonnullByDefault
final class Present<T> extends Optional<T> {
  private final T reference;

  Present(T reference) {
    this.reference = reference;
  }

  @Override
  public boolean isPresent() {
    return true;
  }

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

  @Override
  public T or(T defaultValue) {

            String fieldKey = field.getKey();
            String fieldDescription = "Configure " + fieldKey + ": " + field.getDescription();
            if (field.getOptions().isPresent()) {
                // list options
                ListPromptBuilder listPromptBuilder =
                        promptBuilder.createListPrompt().name(fieldKey).message(fieldDescription);

   *
   * @throws IOException if an I/O error occurs
   * @since 15.0
   */
  public boolean isEmpty() throws IOException {
    Optional<Long> sizeIfKnown = sizeIfKnown();
    if (sizeIfKnown.isPresent()) {
      return sizeIfKnown.get() == 0L;
    }
    Closer closer = Closer.create();
    try {
      InputStream in = closer.register(openStream());
      return in.read() == -1;
    } catch (Throwable e) {

        this.components = components;
    }

    @Override
    public <T> T lookup(Class<T> type) {
        Optional<T> optional = lookupOptional(type);
        if (optional.isPresent()) {
            return optional.get();
        } else {
            throw new LookupException("No mapping for key: " + type.getName());
        }
    }

    @Override