@Entity
public class MainEntity {

    @OneToOne(orphanRemoval = true, cascade = CascadeType.ALL)
    private ChildEntity childEntity;
}

@Entity
public class ChildEntity {

    @OneToMany(cascade = CascadeType.ALL)
    @LazyCollection(FALSE)
    private List<AnotherEntity> otherEntities;

   @PrePersist
    void prePersist(){
        LOG.info(otherEntities); //...................... LINE 30;
    } 
}

@Entity
public class AnotherEntity {
}

@Named
@SessionScoped
public class ApplicationController implements Serializable {
    private static final long serialVersionUID = -1343434343L;

    @EJB
    private ParentEntityFacade parentEntityFacade;

    private ParentEntity parentEntity;

    public void createAndReloadEntity() {
        parentEntity = new ParentEntity();

        final ChildEntity childEntity = new ChildEntity();
        for (int i = 0; i < 10; i++) {
            childEntity.getOtherEntities().add(new AnotherEntity());
        }

        System.out.println(parentEntity);
        parentEntity.setChildEntity(childEntity);
        parentEntityFacade.create(parentEntity);
        this.parentEntity = parentEntityFacade.find(parentEntity.getId());
        System.out.println(parentEntity);
    }

    public void editAndReloadEntity() {
        final ChildEntity childEntity = new ChildEntity();
        for (int i = 0; i < 10; i++) {
            childEntity.getOtherEntities().add(new AnotherEntity());
        }

        System.out.println(parentEntity);
        parentEntity.setChildEntity(childEntity);
        this.parentEntity = parentEntityFacade.edit(parentEntity);
        System.out.println(parentEntity);
    }

}

EntityManager.persust(parentEntity)

EntityManager.merge(parentEntity)