Can it be used without annotating the types

My data objects are created externally, and I cannot annotate them.  Is it possible to serialize/deserialize objects to classes that look like

```
class Thing {
  private String foo;
  private List<String> bar;

  // Getters and setters omitted for brevity
}
```

I know about mixins, but adding mixins to a hundred or so classes is not realistic.