Add an update feature (previously only insert was allowed) but it add…

[Rebolon]

…s more complexity: should i allow update of all nodes when an id is set or only root element of the json string ? what happens on associative entity (ParamConverter must not remove DB entries, so the controller will have to manage this) ? should i block this feature when this is an HTTP POST call ?

[Rebolon]

Code smells in initFromRequest: the system to manage an update is correct for Item but falsy for List
too much complexity for little bit of interest

Don't forget that the aim is to get valid entities, and ParamConverter must not have domain logic.
So i should not care about the fact that it's a POST or a PUT.
It's up to the Controller to decide if it must update evrything, or only root element.