JPA need for explicit .refresh on Entity indepent of CascadeType.REFRESH?

Why isn't my CascadeType.REFRESH actually refreshing my entities? When adding an object it doesn't update the collection (still empty).

I need to explicit call entity.refresh()! Here's my partial code (where .ALL could be replaced with .REFRESH, .PERSIST):

@Entity
public class Event extends Model {
    @OneToMany(mappedBy="event", cascade=CascadeType.ALL)
    public List<Invitation> invitations;
}

@Entity
public class Invitation extends Model 
{
    @ManyToOne(cascade=CascadeType.ALL)
    public Event event;
}


// ..
        Event event = new Event(/* ... */);
        event.save();

        if (invitationid > 0)
        {
         开发者_开发问答   Logger.info("Invitation added to event");
            Invitation invite = Invitation.findById(invitationid);
                invite.event = event;
                invite.save();
        }

        // Explicit calling this, will actually do refresh the object and show the invite.
        // event.refresh();

        if (event.invitations == null || event.invitations.size() == 0)
            Logger.info("Still null?!");
// ..

I'm Play! framework which seems to be shipped with hibernate-jpa-2.0.

You are responsible of the coherence of the object graph. JPA won't automatically add a child to a parent's collection when you save the child. It's thus of your responsibility to do

Invitation invitation = new Invitation();
invitation.setEvent(event);
event.getInvitations().add(invitation);

It's even better to encapsulate this in a addInvitation method of the Event class:

public void addInvitation(invitation) {
    this.invitations.add(invitation);
    invitation.setEvent(this);
}