RestyGWT Must be annotated with JsonTypeInfo

I'm trying to get data via my Restservice. Therefor I'm Having my spring controller and my rest service.

@Path("/user")
public interface UserAdminRestService extends RestService {
    public static class Util {

        private static UserAdminRestService instance;

        /**
         * Returns an instance of the {@link UserAdminRestService}.
         * @return an instance of the UserAdminRestService.
         */
        public static UserAdminRestService getUserAdminRestService() {

            Resource resource = new Resource(GWT.getModuleBaseURL() + "user");
            GWT.log("UserAdmin-Rescource-Path: "+resource.getPath());
            if (instance == null ) {
                instance = GWT.create(UserAdminRestService.class);
            }

            ((RestServiceProxy) instance).setResource(resource);

            return instance;


        }
    }

    @GET
    @PATH("/test")
    @Produces(MediaType.APPLICATION_JSON)
    @Consumes(MediaType.APPLICATION_JSON)
    public void getUsers(MethodCallback<List<GWTUser>> callback);

}

The GWTUser represent my User entity.

public class GWTUser {

    public interface GWTUserJED extends JsonEncoderDecoder<GWTUser> {

    }

    private String userId;

    ... // data

    @Override
    public String toString() {
        if (GWT.isClient()) {
            GWTUserJED jed = GWT.create(GWTUserJED.class);
            return jed.encode(this).toString();
        }
        return super.toString();
    }
}

And I'm trying to call it in my gwt application:

HashMap<String, String> header = new HashMap<String, String>();
header.put(Resource.HEADER_ACCEPT, Resource.CONTENT_TYPE_JSON+"; charset=utf-8");

Resource resourceGetUsers = new Resource("/user/test", header);

UserAdminRestService.Util.getUserAdminRestService().getUsers(new MethodCallback<List<GWTUser>>() {

    @Override
    public void onFailure(Method method, Throwable exception) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onSuccess(Method method, List<GWTUser> response) {
        // TODO Auto-generated method stub

    }

});

But I'm getting an error message when I'm trying to compile my application.

 --- gwt-maven-plugin:2.5.1:compile (default-cli) @ myapp-admin-gwt ---
 auto discovered modules [com.myapp.admin.gwt]
 Compiling module com.myapp.admin.gwt
    Computing all possible rebind results for 'com.myapp.admin.rest.UserAdminRestService'
       Rebinding com.myapp.admin.rest.UserAdminRestService
          Invoking generator org.fusesource.restygwt.rebind.RestServiceGenerator
             Generating: com.myapp.admin.rest.UserAdminRestService_Generated_RestServiceProxy_
                Generating: com.google.gwt.http.client.Response_Generated_JsonEncoderDecoder_
                   [ERROR] Abstract classes must be annotated with JsonTypeInfo
    [ERROR] Errors in 'com/myapp/admin/rest/UserAdminRestService.java'
       [ERROR] Line 53: Failed to resolve 'com.myapp.admin.rest.UserAdminRestService' via deferred binding
    [WARN] For the following type(s), generated source was never committed (did you forget to call commit()?)
       [WARN] com.myapp.admin.rest.UserAdminRestService_Generated_RestServiceProxy_
       [WARN] com.google.gwt.http.client.Response_Generated_JsonEncoderDecoder_

So I'm not sure what to do. Do I need an JsonTypeInfo for my Service, but what for?! Or do I need to make my GWTUser abstract and add a JsonTypeInfo. Thanks for any help.

Not sure but might be linked to the fact that your GWTUser has an interface inside that RestyGWT cannot resole.

Try moving out your JsonEncoderDecoder outside your User class.