From: Jay Bloodworth <johnabloodworth3_at_gmail.com>
Date: Mon, 27 Sep 2010 06:03:19 -0400

 On 09/26/2010 11:23 PM, Ronak Patel wrote:
> Jay,
>
> You cannot set an @Id of a JPA Entity that is a @GeneratedValue.
>
>

Thank you for your reply. For what it's worth, the following works:

@PUT
@Consumes("application/json")
@Produces("text/html")
@Path("{id}")
public String doUpdate(@PathParam id, Entity entity) {
    entity.setId(id);
    entity = em.merge(entity);
    // entity.setId(something); <--- throws an exception for accessing
id field
    return "Success";
}

So it appears that you can set the id field on an entity in an unmanaged
state. But then I still think it's weird that the marshalling code
doesn't set it.

Jay