public static String substVars(String val, PropertyContainer pc1) throws ScanException {
        return substVars(val, pc1, null);
    }
@Test
    public void recursionErrorWithNullLiteralPayload() throws ScanException {

        Exception e = assertThrows(IllegalArgumentException.class, () -> {
           OptionHelper.substVars("abc${AA$AA${}}}xyz", context);
        });
        String expectedMessage = CIRCULAR_VARIABLE_REFERENCE_DETECTED+"${AA} --> ${}]";
        assertEquals(expectedMessage, e.getMessage());
    }