public void test_append_nullPrinter_Parser() {
        DateTimeFormatterBuilder bld = new DateTimeFormatterBuilder();
        bld.appendLiteral('Y');
        DateTimeParser p = bld.toParser();
        
        try {
            DateTimeFormatterBuilder bld2 = new DateTimeFormatterBuilder();
            bld2.append((DateTimePrinter) null, p);
            fail();
        } catch (IllegalArgumentException ex) {
            // expected
        }
    }