public void test_toLowerHyphen_nullValues() {
        Map<String, Object> source = new HashMap<>();
        source.put("AnotherKey", "anotherValue");
        source.put("ValidKey", "validValue");

        Map<String, Object> result = searchLogHelper.toLowerHyphen(source);

        assertEquals("anotherValue", result.get("another_key"));
        assertEquals("validValue", result.get("valid_key"));
    }