code: final byte[] decodeChecked(CharSequence chars)
        throws DecodingException {
      chars = trimTrailingPadding(chars);
      byte[] tmp = new byte[maxDecodedSize(chars.length())];
      int len = decodeTo(tmp, chars);
      return extract(tmp, len);
    }
docs: Decodes the specified character sequence, and returns the resulting {@code byte[]}. This is the
  inverse operation to {@link #encode(byte[])}.
  
  @throws DecodingException if the input is not a valid encoded string according to this
  encoding.