Issue with ResponseFormatException with polymorphism

[nloke]

First of all I am using restygwt 2.0.2 which I have recently upgraded from 1.X.
Since the upgrade, I am forced to defined every Dto that has extends with proper JsonSubTypes and JsonTypeNames.

Following is the scenario that is falling for me

Given I have the super class, A as below.

@JsonSubTypes({@Type(A.class), @Type(B.class)})
@JsonTypeName("A")
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "@class")
public class A {
    private String code;

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }
}

and a subclass B as below:

@JsonTypeName("B")
public class B extends A {
    private String desc;

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc= desc;
    }
}

Using Spring MVC (version 3.2.0.RELEASE) I have the following on the server side.

@RequestMapping(method = GET, produces = JSON_TYPE)
public ResponseEntity<List<A>> getA(@RequestParam(CODE) String code) {
    A dto= new A();
    dto.setCode("test code")
    List<A> dtoList= Lists.newArrayList(dto);

    return new ResponseEntity<List<A>>(dtoList, HttpStatus.OK);
}

When the json string is returned from the server it will be

[
    {"code":"test code"}
]

As observed it is missing the "@Class":A which will eventually cause the ResponseFormatException because the generated JsonEncoderDecoder for A will check for sourceName and expects it to be not NULL because A is not a leaf due to B being its subtype.

Is this an actual problem with the way I defined the subtypes? or
Is this a problem with Spring MVC's MappingJackson2HttpMessageConverter not having the "@Class" property in the json response? or
Is this as actual issue with the JsonEncoderDecoderClassCreator where it should also consider the case where there potentially no sourceName is provided?