Hibernate @OneToMany doesn't link child and parent on save

@Entity
@Table(name = "parent")
@NoArgsConstructor
@AllArgsConstructor
@SequenceGenerator(name = "parentSequence", sequenceName = "parent_id_seq",
        allocationSize = 1)
public class ParentDto implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "parentSequence")
    private Long id;
    
    private String name;

    @OneToMany(mappedBy = "parent")
    private List<Child> children;
}


@Entity
@AllArgsConstructor
@SequenceGenerator(name="childSequence", sequenceName = "child_id_seq", allocationSize=1)
@Table(name = "child")
public class Child{
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "childSequence")
    private Long id;

    private String name;

    @ManyToOne
    @JoinColumn(name = "parent_id", nullable = false)
    private Parent parent;
}

I have the next request to save mapped to property request (ids should be generated by DB)

{
    "parent": {
       "name": "Bob",
       "children": [{
            "name": "Bob2"
       }]
    }
}

Executing parentDao.save(request); and trying to get child executing childDao.findAll(); which returns empty array. When executing parentDao.findAll() - receiving parent which contains child object with id=null and parent=null. Also while performing parentDao.save(request) with updated data getting such exception

Unable to find ChildDto with id 1; nested exception is javax.persistence.EntityNotFoundException: Unable to find ChildDto with id 1

If I update ParentDto with

@OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private List<Child> children;

receive such exception

Caused by: org.hibernate.PersistentObjectException: detached entity passed to persist: ChildDto