+ StringUtils.leftPad(String.valueOf(digits), CONTROL_DIGITS_LENGTH);
+ StringUtils.leftPad(String.valueOf(digits), CONTROL_DIGITS_LENGTH, CODE_FILLER);
    private static String generateFinalCode(final PaymentCodeType paymentCodeType,	    final Student student, int digits) {	final String finalCode = getCodePrefix(paymentCodeType, student)		+ StringUtils.leftPad(String.valueOf(digits), CONTROL_DIGITS_LENGTH);	if (finalCode.length() != CODE_LENGTH) {	    throw new RuntimeException("Unexpected code length for generated code");	}	return finalCode;    }