@Entity
@Table(name="EntityDO")
public class EntityDO {
    @Id
    private Long id;

    @Column(nullable = false)
    private String name;

    @OneToMany(mappedBy = "parentEntity")
    private Set<EntityDO> ownedEntities;

    @ManyToOne
    @JoinColumn(name="PARENT_ID", nullable=true)
    private EntityDO parentEntity;

    ...
}