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 {

      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 {

      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 {

    }

    ByteBuffer buf = ByteBuffer.wrap(createBuffer());
    long total = 0;
    while (from.read(buf) != -1) {
      Java8Compatibility.flip(buf);
      while (buf.hasRemaining()) {
        total += to.write(buf);
      }
      Java8Compatibility.clear(buf);
    }
    return total;
  }

  /** Max array length on JVM. */
  private static final int MAX_ARRAY_LEN = Integer.MAX_VALUE - 8;