Investigate how to reduce the need for `@JsonSerialize`

To JSON serialize the proxied objects that are the result of using `@AuthorizeReturnObject`, it's necessary to [annotate the proxied object](https://docs.spring.io/spring-security/reference/servlet/authorization/method-security.html#_working_with_jackson) with something like:

```
@JsonSerialize(as = MyObject.class)
```

It would be nice if this boilerplate weren't necessary.