public static String substVars(String val, PropertyContainer pc1) throws ScanException {
        return substVars(val, pc1, null);
    }
@Test
    public void testUndefinedValues() throws ScanException {
        String withUndefinedValues = "${axyz}";

        String result = OptionHelper.substVars(withUndefinedValues, context);
        assertEquals("axyz" + OptionHelper._IS_UNDEFINED, result);
    }