List<byte[]> getPasswordBytes(boolean unicodeConversion) {
        // TODO - handle unicodeConversion when we support version 5
        if (this.passwordBytes != null || this.passwordString == null) {
            return Collections.singletonList(this.passwordBytes);
        } else {
            if (isAlphaNum7BitString(this.passwordString)) {
                // there's no reasonthat this string would get encoded
                // in any other way
                return Collections.singletonList(
                        PDFStringUtil.asBytes(passwordString));
            } else {
                return generatePossiblePasswordBytes(passwordString);
            }
        }
    }