The HotelBookingAction (SFSB) has an method that begins the long-running conversation (@Begin) called selectHotel(Hotel selectedHotel) . See below:
@Stateful
@Name("hotelBooking")
@Restrict("#{identity.loggedIn}")
public class HotelBookingAction implements HotelBooking
{
@PersistenceContext(type=EXTENDED)
private EntityManager em;
...
@In(required=false) @Out
private Hotel hotel;
@In(required=false)
@Out(required=false)
private Booking booking;
...
@Begin
public void selectHotel(Hotel selectedHotel)
{
hotel = em.merge(selectedHotel);
}
@End
public void confirm()
{
em.persist(booking);
facesMessages.add("Thank you, #{user.name}, your confimation number for #{hotel.name} is #{booking.id}");
log.info("New booking: #{booking.id} for #{user.username}");
events.raiseTransactionSuccessEvent("bookingConfirmed");
}
...
}
The question is:
why does use em.merge on 'selectedHotel'? What about em.find(Hotel.class, selectedHotel.getId())? 
