import ch.codeblock.qrinvoice.util.QRReferenceUtils;
// ...
// QR references can be created without restrictions from numeric input with up to 26 digits, the 27th digit is used as check digit
final String qrReference = QRReferenceUtils.createQrReference("127");
System.out.println(qrReference);
// prints 000000000000000000000001273