* https://github.com/google/guava/issues/3990
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class Java8Compatibility {
  static void clear(Buffer b) {
    b.clear();
  }

  static void flip(Buffer b) {
    b.flip();
  }

  static void limit(Buffer b, int limit) {
    b.limit(limit);
  }

@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class Java8Compatibility {
  static void clear(Buffer b) {
    b.clear();
  }

  static void flip(Buffer b) {
    b.flip();
  }

  static void limit(Buffer b, int limit) {
    b.limit(limit);
  }

  static void position(Buffer b, int position) {
    b.position(position);
  }

  private Java8Compatibility() {}

 * https://github.com/google/guava/issues/3990
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class Java8Compatibility {
  static void clear(Buffer b) {
    b.clear();
  }

  static void flip(Buffer b) {
    b.flip();
  }

  static void limit(Buffer b, int limit) {
    b.limit(limit);
  }

  private static CharBuffer grow(CharBuffer buf) {
    char[] copy = Arrays.copyOf(buf.array(), buf.capacity() * 2);
    CharBuffer bigger = CharBuffer.wrap(copy);
    Java8Compatibility.position(bigger, buf.position());
    Java8Compatibility.limit(bigger, buf.limit());
    return bigger;
  }

  /** Handle the case of underflow caused by needing more input characters. */
  private void readMoreChars() throws IOException {

  private static CharBuffer grow(CharBuffer buf) {
    char[] copy = Arrays.copyOf(buf.array(), buf.capacity() * 2);
    CharBuffer bigger = CharBuffer.wrap(copy);
    Java8Compatibility.position(bigger, buf.position());
    Java8Compatibility.limit(bigger, buf.limit());
    return bigger;
  }

  /** Handle the case of underflow caused by needing more input characters. */
  private void readMoreChars() throws IOException {

    }

    checkNotNull(from);
    checkNotNull(to);
    long total = 0;
    CharBuffer buf = createBuffer();
    while (from.read(buf) != -1) {
      Java8Compatibility.flip(buf);
      to.append(buf);
      total += buf.remaining();
      Java8Compatibility.clear(buf);
    }
    return total;
  }

  // TODO(lukes): consider allowing callers to pass in a buffer to use, some callers would be able

    Java8Compatibility.flip(buf2);
    assertEquals(expected, buf2.toString());
    assertFullyRead(reader);

    // read in chunks to fixed CharBuffer
    reader = new CharSequenceReader(charSequence);
    buf2 = CharBuffer.allocate(5);
    builder = new StringBuilder();
    while (reader.read(buf2) != -1) {
      Java8Compatibility.flip(buf2);
      builder.append(buf2);

      StringBuilder builder = new StringBuilder();
      CharBuffer buffer = CharBuffer.allocate(100);
      while (reader.read(buffer) != -1) {
        Java8Compatibility.flip(buffer);
        builder.append(buffer);
        Java8Compatibility.clear(buffer);
      }
      return builder.toString();
    }
  }

  private static class UrlByteSourceFactory extends FileByteSourceFactory {

   * @throws IOException if an I/O error occurs
   */
  @CanIgnoreReturnValue // to skip a line
  @CheckForNull
  public String readLine() throws IOException {
    while (lines.peek() == null) {
      Java8Compatibility.clear(cbuf);
      // The default implementation of Reader#read(CharBuffer) allocates a
      // temporary char[], so we call Reader#read(char[], int, int) instead.

      StringBuilder builder = new StringBuilder();
      CharBuffer buffer = CharBuffer.allocate(100);
      while (reader.read(buffer) != -1) {
        Java8Compatibility.flip(buffer);
        builder.append(buffer);
        Java8Compatibility.clear(buffer);
      }
      return builder.toString();
    }
  }

  private static class UrlByteSourceFactory extends FileByteSourceFactory {