Why is @Veto a best practice for persistent (JPA) entities?

Adding the @Veto annotation to all persistent entities is considered a best practice in most cases. The purpose of this annotation is to prevent the BeanManager from managing an entity as a Bean. This feature is currently made available to Seam Solder 3.0 and is proposed for the coming CDI 1.1 specifiction.

When an entity is annotated @Veto no injections will take place. The reasoning behind this is to prevent the BeanManager to perform operations that may cause the JPA provider to break.

In Seam Persistence a post-load lifecycle is added to enable post injection.

@Entity
@Veto
public class Foo
{
   /* This will not be respected by the BeanManager */
   @Inject
   private Logger log;

   /* This annotation is managed by the EnityManager and not the BeanManager */
   @Column
   private String bar; 
}

All JPA persistent entities should be marked with @Veto as this will prohibit BeanManager to interfere with the EntityManager, This includes MappedSuperclass, Embedded, ModelListeners, etc.

You can also annotate a package-info.java to let a whole package be marked veto.