return new Base64Encoding(alphabet, paddingChar);
    }
  }

  @J2ktIncompatible
  @GwtIncompatible
  static Reader ignoringReader(Reader delegate, String toIgnore) {
    checkNotNull(delegate);
    checkNotNull(toIgnore);
    return new Reader() {
      @Override
      public int read() throws IOException {
        int readChar;