public static String substVars(String val, PropertyContainer pc1) throws ScanException {
        return substVars(val, pc1, null);
    }
@Test
    public void leftAccoladeFollowedByDefaultStateWithNoLiteral() throws ScanException {
        Exception e = assertThrows(ScanException.class, () -> {
            OptionHelper.substVars("x{:-a}", context);
        });
        String expectedMessage = EXPECTING_DATA_AFTER_LEFT_ACCOLADE;
        assertEquals(expectedMessage, e.getMessage());
    }