I am trying to use Omnipersistence for the first time on a new Maven project and get the following error in Eclipse: The entity has no primary key attribute defined

import org.omnifaces.persistence.model.TimestampedEntity;
@Entity
public class ShoppingCart extends TimestampedEntity<Long> {

    ...
}

While trying to figure out the issue, I happened to add a constructor with this.id = id, and Eclipse gave a warning that stated id is not visible but when I control-clicked on id, it took me to the TimestampedEntity class.