@Entity
public class Parent {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  @OneToMany(cascade = CascadeType.ALL, mappedBy = "parent", orphanRemoval = true, fetch = FetchType.EAGER)
  @OrderColumn(name = "pos")
  private List<Child> childs;

  ...
}

@Entity
public class Child {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  private int pos;

  @ManyToOne(fetch = FetchType.EAGER)
  @JoinColumn(name = "parent_id")
  private Parent parent;
  
  ...
}

SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
Session session = sessionFactory.getCurrentSession();

Transaction tx = session.beginTransaction();
session.save(new Parent(Arrays.asList(new Child(), new Child())));
tx.commit();

sessionFactory.close();

Hibernate: insert into Parent (id) values (default)
Hibernate: insert into Child (id, parent_id, pos) values (default, ?, ?)
Hibernate: insert into Child (id, parent_id, pos) values (default, ?, ?)
Hibernate: update Child set pos=? where id=?
Hibernate: update Child set pos=? where id=?