Spring Data JPAのテーブル結合においてユニークな属性を持ちたい。

###Spring Data JPAのテーブルでユニークな属性を持ちたい
多対多のテーブルで、insertの制御がしたいです。

###発生している問題・エラーメッセージ

ユニーク属性が保てていません。

想定

Room
id, name
1, tubaki
2, sakura

Equipment
id, name
1, fork
2, spoon

Quota(交差テーブル)
room_id, equipment_id
1, 1
1, 2
2, 1

Equipment
id, name
1, fork
2, spoon
3, fork

Quota
room_id, equipment_id
1, 1
1, 2
2, 3

となってしまいます。

###該当のソースコード

java
1 public class Room implements Serializable {
2    @Id
3    @GeneratedValue
4    @Column(name = "room_id")
5    private Integer roomId;
6
7    @NotNull
8    @Column(unique = true)
9    private String roomName;
10
11    private Integer capacity;
12
13    @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
14    @JoinTable(
15            name = "quota",
16            joinColumns = {@JoinColumn(name = "room_id", referencedColumnName = "room_id")},
17            inverseJoinColumns = {@JoinColumn(name = "equipment_id", referencedColumnName = "equipment_id")}
18    )
19    private List<Equipment> equipments;
20    /* 以下getter, setter */

java
1    @Entity
2    public class Equipment implements Serializable {
3    @Id
4    @GeneratedValue
5    @Column(name = "equipment_id")
6    private Integer equipmentId;
7
8    @Column
9    private String equipmentName;
10
11    @ManyToMany(mappedBy = "equipments")
12    private List<Room> rooms;
13    /* 以下 getter, setter */

正規化のmigrateを想定しています。migrate(insert)のコードはこちらになります。

java
1    public void migrate() {
2        roomService.truncateRoom();
3
4        equipmentRoomRepository.findAll().stream().collect(
5                Collectors.groupingBy(EquipmentRoom::getRoomName)
6        ).forEach((roomName, equipmentRooms) -> {
7            int capacity = equipmentRooms.get(0).getCapacity();
8
9            List<Equipment> equipments = equipmentRooms.stream()
10                    .map(equipmentRoom -> new Equipment(equipmentRoom.getEquipmentName()))
11                    .collect(Collectors.toList());
12
13            roomRepository.save(new Room(roomName, capacity, equipments));
14
15        });
16    }

テストコードです。

java
1     private static final List<EquipmentRoom> equipmentRooms = Arrays.asList(
2            new EquipmentRoom("sakura", 2, "fork"),
3            new EquipmentRoom("sakura", 2, "spoon"),
4            new EquipmentRoom("tsubaki", 3, "fork")
5    );
6
7    @Before
8    public void SetUp() {
9        equipmentRoomRepository.truncateTable();
10        equipmentRoomRepository.save(equipmentRooms);
11    }
12
13    @Test
14    public void migrateTest() {
15        equipmentRoomMigrateService.migrate();