}

    @Override
    public boolean canDecode(CharSequence chars) {
      checkNotNull(chars);
      chars = trimTrailingPadding(chars);
      if (!alphabet.isValidPaddingStartPosition(chars.length())) {
        return false;
      }
      for (int i = 0; i < chars.length(); i++) {
        if (!alphabet.canDecode(chars.charAt(i))) {
          return false;
        }
      }