protected static Map<String, String> appendParameter(Map<String, String> parameters, String key, String value) {
        if (parameters == null) {
            parameters = new HashMap<>();
        }
        parameters.put(key, value);
        return parameters;
    }
@Test
    void appendParameter() {
        Map<String, String> source = null;

        Map<String, String> parameters = new HashMap<>();
        parameters.put("default.num", "one");
        parameters.put("num", "ONE");
        source = AbstractBuilder.appendParameters(source, parameters);

        Assertions.assertTrue(source.containsKey("default.num"));
        Assertions.assertEquals("ONE", source.get("num"));
    }