* @since 19.0
   */
  public long length() throws IOException {
    Optional<Long> lengthIfKnown = lengthIfKnown();
    if (lengthIfKnown.isPresent()) {
      return lengthIfKnown.get();
    }

    Closer closer = Closer.create();
    try {
      Reader reader = closer.register(openStream());
      return countBySkipping(reader);

   * @since 19.0
   */
  public long length() throws IOException {
    Optional<Long> lengthIfKnown = lengthIfKnown();
    if (lengthIfKnown.isPresent()) {
      return lengthIfKnown.get();
    }

    Closer closer = Closer.create();
    try {
      Reader reader = closer.register(openStream());
      return countBySkipping(reader);

  @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) {

                          && (m.getModifiers() & (PUBLIC | PROTECTED | PRIVATE)) == 0)
              .transform(Method::getDeclaringClass);
      if (!supersWithPackagePrivateWriteReplace.isPresent()) {
        continue;
      }
      assertWithMessage(
              "To help optimizers, any class that inherits a package-private writeReplace() method"
                  + " should override that method.\n"

      @Override
      String read(ByteSource byteSource, Charset cs) throws IOException {
        Optional<Long> size = byteSource.sizeIfKnown();
        // if we know the size and it fits in an int
        if (size.isPresent() && size.get().longValue() == size.get().intValue()) {
          // otherwise try to presize a StringBuilder
          // it is kind of lame that we need to construct a decoder to access this value.

     *
     * @return ActionResponse directing to the appropriate page based on authentication result
     */
    @Execute
    public ActionResponse index() {
        if (fessLoginAssist.getSavedUserBean().isPresent()) {
            return redirectToSearchPage().orElseGet(() -> {
                if (logger.isDebugEnabled()) {
                    logger.debug("User is already logged in, redirecting to root.");
                }

   */
  private static boolean matchesType(
      Optional<PublicSuffixType> desiredType, Optional<PublicSuffixType> actualType) {
    return desiredType.isPresent() ? desiredType.equals(actualType) : actualType.isPresent();
  }

  /** Returns the domain name, normalized to all lower case. */
  @Override
  public String toString() {
    return name;
  }

  /**

   * exceptions thrown from the test do not cause this check to fail.
   */
  @RegisterExtension
  val noDataLeftBehind =
    AfterEachCallback { context: ExtensionContext ->
      if (context.executionException.isPresent) return@AfterEachCallback
      assertThat(data.readByteString().hex(), "Data not empty")
        .isEqualTo("")
    }

  // Mutually exclusive. Use the one corresponding to the peer whose behavior you wish to test.

     */
    @Execute
    public JsonResponse<ApiResult> list(final OptionalThing<String> id) {
        final List<Map<String, Object>> list = getFileItems(id.isPresent() ? decodePath(id.get()) : null);
        try {
            return asJson(new ApiResult.ApiStorageResponse().items(list).status(ApiResult.Status.OK).result());
        } catch (final ResultOffsetExceededException e) {

    assertEquals(expected.length(), source.length());
  }

  public void testLengthIfKnown() throws IOException {
    Optional<Long> lengthIfKnown = source.lengthIfKnown();
    if (lengthIfKnown.isPresent()) {
      assertEquals(expected.length(), (long) lengthIfKnown.get());
    }
  }

  public void testReadLines_withProcessor() throws IOException {
    List<String> list =
        source.readLines(