@Entity(name = "sample_entity")
public class SampleEntity {

    @Id
    @GeneratedValue()
    private Integer id;

    @ManyToMany
    @JoinTable(name = "entity_relationship",
            joinColumns = {@JoinColumn(name = "entity_id")},
            inverseJoinColumns = {@JoinColumn(name = "relationship_id")})
    @OrderColumn(name = "relationship_order")
    private List<SampleEntity> relationships = new ArrayList<SampleEntity>();
}

create table entity_relationship (
        entity_id integer not null,
        relationship_id integer not null,
        relationship_order integer not null,
        primary key (entity_id, relationship_order)
    )