}

    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