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);

  @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) {

  @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) {

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

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

  public void testContentEquals() throws IOException {
    assertTrue(
        source.contentEquals(

    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);

    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(

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

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

  public void testContentEquals() throws IOException {
    assertTrue(
        source.contentEquals(

                          && (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"

                          && (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.