how should i convert a map to json String with gson

My code likes:

    @Test
    public void testGsonTransferMap(){
        HashMap<String, Object> map = new HashMap<String, Object>() {{
            put("Request", new HashMap<String ,Object>(){{
                put("Data",new HashMap<String,Object>(){{
                    put("NWExID", "7019");
                    put("OrgOrderNo", "123");
                    put("OrgTransDate", "20170518");
                }});
            }});
        }};
        Gson gson = new Gson();
        Type gsonType = new TypeToken<HashMap<String ,Object>>(){}.getType();
        String gsonString = gson.toJson(map,gsonType);
        System.out.println(gsonString);
    } 

and the output is : “{}” so,what’s wrong with my code , how should i do.

[JakeWharton]

Yes. This is working as intended.

[NightlyNexus]

You are trying to serialize an anonymous inner class. Don’t.