assertThat(Stream.empty().collect(toOptional())).isEmpty();
  }

  public void testToOptionalSingleton() {
    assertThat(Stream.of(1).collect(toOptional())).hasValue(1);
  }

  public void testToOptionalNull() {
    Stream<@Nullable Object> stream = Stream.of((Object) null);
    assertThrows(NullPointerException.class, () -> stream.collect(toOptional()));
  }

  public void testToOptionalMultiple() {

   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.
   */
  @SuppressWarnings("unchecked")
  public static <T> Collector<T, ?, Optional<T>> toOptional() {
    return (Collector) TO_OPTIONAL;
  }

  private static final Object NULL_PLACEHOLDER = new Object();

 */
@DoNotMock("Use Optional.of(value) or Optional.absent()")
@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
public abstract class Optional<T> implements Serializable {
  /**
   * Returns an {@code Optional} instance with no contained reference.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this method is equivalent to Java 8's
   * {@code Optional.empty}.
   */
  public static <T> Optional<T> absent() {

  }

  public void testToJavaUtil_instance() {
    assertEquals(java.util.Optional.empty(), Optional.absent().toJavaUtil());
    assertEquals(java.util.Optional.of("abc"), Optional.of("abc").toJavaUtil());
  }

  @SuppressWarnings("NullOptional")
  public void testFromJavaUtil() {
    assertNull(Optional.fromJavaUtil(null));

     *
     * @return an {@link Optional} containing the map of user properties, or empty if not set
     */
    @Nonnull
    Optional<Map<String, String>> userProperties();

    /**
     * Indicates whether to show the version information and exit.
     *
     * @return an {@link Optional} containing the boolean flag, or empty if not set
     */
    @Nonnull
    Optional<Boolean> showVersionAndExit();

    /**

        serialization_alias: Union[str, None] = None,
        title: Optional[str] = None,
        description: Optional[str] = None,
        gt: Optional[float] = None,
        ge: Optional[float] = None,
        lt: Optional[float] = None,
        le: Optional[float] = None,
        min_length: Optional[int] = None,
        max_length: Optional[int] = None,
        pattern: Optional[str] = None,
        regex: Annotated[
            Optional[str],

        }
        return Optional.empty();
    }

    @Override
    public Optional<Boolean> nonRecursive() {
        if (commandLine.hasOption(CLIManager.NON_RECURSIVE)) {
            return Optional.of(Boolean.TRUE);
        }
        return Optional.empty();
    }

    @Override
    public Optional<Boolean> updateSnapshots() {
        if (commandLine.hasOption(CLIManager.UPDATE_SNAPSHOTS)) {

			Optional:    true,
			Type:        "string",
			Sensitive:   true,
			Secret:      true,
		},
		config.HelpKV{
			Key:         target.WebhookQueueDir,
			Description: queueDirComment,
			Optional:    true,
			Type:        "path",
		},
		config.HelpKV{
			Key:         target.WebhookQueueLimit,
			Description: queueLimitComment,
			Optional:    true,
			Type:        "number",
		},

			Optional:    true,
			Type:        "string",
			Sensitive:   true,
		},
		config.HelpKV{
			Key:         BatchSize,
			Description: "Number of events per HTTP send to webhook target",
			Optional:    true,
			Type:        "number",
		},
		config.HelpKV{
			Key:         QueueSize,
			Description: "configure channel queue size for webhook targets",
			Optional:    true,
			Type:        "number",

    name: Optional[str] = None
    call: Optional[Callable[..., Any]] = None
    request_param_name: Optional[str] = None
    websocket_param_name: Optional[str] = None
    http_connection_param_name: Optional[str] = None
    response_param_name: Optional[str] = None
    background_tasks_param_name: Optional[str] = None
    security_scopes_param_name: Optional[str] = None