Vaadin 8 - TwinColSelect with dataprovider

Hello guys,

Can’t achieve something trivial, can somebody help me ?

final TwinColSelect<Fare> select = new TwinColSelect<Fare>();
select.setDataProvider(dataProvider);
select.setItemCaptionGenerator(Fare::getLabel);
select.setValue(entity.getFares());

With this simple code, I can display available values (in the left column), but already saved values (left column) never display.
I suspect that the component does not compare correctly both objects (from dataprovider and from existing entity)
(entities are JPA objects)

Regards
Sebastien