Allow to set an annotation on an Object param to automatically wrap it

Something like

```
@Class("pkg.SomeClass")
public interface {
// original method : String computeThing(int, String, InternalHidden)
String computeThing(int uid, String name, @Class("pkg.InternalHidden") Object template);
}
```

Begin with the Java and Android reflection behavior represented by the proposed computeThing signature. Determine how an annotation on an Object parameter should identify the wrapped class, and define tests showing that the example automatically wraps the template while preserving the original method contract.

Written by the indexing model from the issue text.