{
"request": {
        " TestRequest": {
            "OrderID": {
                "orderNumber": "12345",
                "category": "ABC"
            },
            "SecondCategory": "DEF"
        }
    }
}

JObject jObject = new JObject(new JProperty("request",
                  new JObject(
                    new JProperty("TestRequest",
                    new JObject(
                        new JProperty("OrderID",
                            new JProperty("orderNumber", "12345"),
                            new JProperty("category", "ABC")),
                            new JProperty("SecondCategory", "DEF")))))
                );