- [ ] add typed setters for system parameters - [ ] take care in case of enums - [x] add Application#converters/authenticators and remove magic discovery in Engine - [ ] add Component#clients/servers and remove magic discovery in Engine - [ ] document (in the [wiki](https://github.com/restlet/restlet-framework-java/wiki/Migration-to-3.0) for the moment)
