To configure Genson instances you can use Genson.Builder class (it is similar to Gson on this point). Then you have to inject it with Jersey.
@Component
@Provider
public class GensonProvider implements ContextResolver<Genson> {
private final Genson genson = new Genson.Builder().setDateFormat(yourDateFormat).create();
@Override
public Genson getContext(Class<?> type) {
return genson;
}
}
You might also want to have a look at how Genson is integrated into Jersey here.