Returning a collection - transferHandlers to be called

Given an exposed interface.

```
interface Service {
find: (x) => ClassInstance
findAll: (x)=> ClassInstance[]
}
```

I can properly call both methods - but the transferHandlers implementing `ClassInstance` does not get called when handling the response from `findAll` method - resulting in issues on the other side.

Are nested - non-transferable objects expected to be serialized by default? Implementation says no since only the root return value is passed to `toWireValue` .

Is it expected that the custom transferHandlers should inspect canHandle values for expected collections and serialize them directly?