serialize plain object to multi-level json (`@JsonWrap[ped]`)

```
public class Member{
    private String id;
    @JsonProperty("User.name")
    private String name;
    @JsonProperty("User.age")
    private Integer age;
}
```
I expect the serialization is 
```
{
  "id":null,
   "User":{
        "name":null,
        "age": null
   }
}
```