@FeignClient is not failing in Type Mismatch

Question

I am intentionally trying to simulate a failure condition. I have a service which returns JSON of a User object. However, in @FeignClient @RequestMapping I am returning another object i.e. Event.

In this case, I was expecting Feign to fail deserializing the JSON to the Event POJO. But it is not failing. Moreover, the response Event object is also not null.

So my question is, is this the behavior by design? What I can do to make Feign fail in this kind of situation.

Here is my FeignClient.

@FeignClient(name = "userProxy", url = "${securei.url}")
public interface UserProxy {

    @RequestMapping(value = IUser.USER_LOGIN, method = RequestMethod.GET, params = {"u", "p"})
    public Event login(@RequestParam("u") String username, @RequestParam("p") String password);

}

Here the actual login service returns the User JSON, however I have provided Event as the return type. Still, it is not failing.