Given Hibernate 6.4.4 and the following entities:

@Entity
@Getter
@Setter
public class Parent {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Long id;
    @OneToMany(mappedBy = "parentId")
    private List<Child> children;
}

@Entity
@Getter
@Setter
public class Child {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Long id;
    private Long parentId;
}

to my surprise, I can successfully execute a JPQL query like

SELECT p FROM Parent p LEFT JOIN FETCH p.children

or I can load a Parent entity and lazily load its children by invoking getChildrent(). Also I can save and update both Parent and Child entities independently.

I have the following questions regarding @OneToMany(mappedBy = "parentId"):

1. Is pointing OneToMany.mappedBy to a field of a basic type a documented feature? From what I see both Hibernate documentation and JPA specification only describe cases where OneToMany.mappedBy references a field with a parent entity type and corresponding @ManyToOne association.
2. Are there any pitfalls to this approach, considering that I am not interested in cascade operations?
3. What would be the difference between @OneToMany(mappedBy = "parentId") and @OneToMany + @JoinColumn(name = "parent_id") in this case?