Incorrect schema/example with `@EmbeddedId` + relations (Spring Data REST)

[dpkass]

Summary
With JPA @EmbeddedId/@MapsId join entities and Spring Data REST, springdoc generates recursively nested examples instead of compact, reference-like shapes. This misleads client generators and bloats the OpenAPI.

Environment

• Spring Boot + Spring Data JPA + Spring Data REST (HAL)
• springdoc: 2.8.14

---

Minimal model (flattened for clarity)

@Embeddable
class GoalInitiativeImpactId { Long goalId; Long initiativeId; }

@Entity
class Goal {
  @Id @GeneratedValue Long id;
  String name;
  // other fields

  @OneToMany(mappedBy = "goal", cascade = CascadeType.ALL, orphanRemoval = true)
  Set<InitiativeImpactOnGoal> impactsByInitiatives = new HashSet<>();
}

@Entity
class Initiative {
  @Id @GeneratedValue Long id;
  String name;
  // other fields
}

@Entity
class InitiativeImpactOnGoal {
  @EmbeddedId GoalInitiativeImpactId id;
  @ManyToOne @MapsId("goalId") Goal goal;
  @ManyToOne @MapsId("initiativeId") Initiative initiative;
  @Enumerated(EnumType.STRING) ImpactLevel impactLevel;
}

Repositories are exposed via Spring Data REST.

---

Actual (runtime showcase) — request & response

Request
GET /goals/1

Response (trimmed)

{
  "id": 1,
  "name": { "en-US": "string" },
  "impactsByInitiatives": [
    {
      "impactLevel": "TRIVIAL",
      "_links": {
        "goal": { "href": "/goals/1" },
        "initiative": { "href": "/initiatives/42" }
      }
    }
  ],
  "_links": {
    "self": { "href": "/goals/1" },
    "indicators": { "href": "/goals/1/indicators" },
    "parent": { "href": "/goals/1/parent" }
  }
}

The join entity appears as an item with impactLevel + HAL links.

---

Generated by springdoc (Swagger UI example) — problematic (trimmed)

{
  "id": 1,
  "name": { "en-US": "string" },
  "description": { "en-US": "string" },
  "workflowStatus": "DRAFT",
  "impactsByInitiatives": [
    {
      "id": { "goalId": 1, "initiativeId": 42 },
      "goal": {
        "id": 1,
        "name": { "en-US": "string" },
        "parent": {
          "id": 7,
          "parent": { /* … nests again … */ }
        },
        "initiatives": [
          {
            "id": 42,
            "name": "string",
            "payments": [ { /* … */ } ],
            "progressLog": [ { /* … */ } ]
          }
        ],
        "children": [ { /* … */ } ]
      },
      "initiative": {
        "id": 42,
        "name": "string",
        "payments": [ { /* … */ } ],
        "progressLog": [ { /* … */ } ]
      },
      "impactLevel": "TRIVIAL"
    }
  ],
  "_links": {
    "self": { "href": "/goals/1" }
  }
}

Issue: deep recursion and full entity expansion inside the join entity, unlike the HAL representation actually returned at runtime.

---

Expected

Reflect the actual shape for read operations. For write ops we can just use READ_ONLY ourselves.

---

Workarounds (short)

• Expose DTOs/projections for REST (flatten associations).
• Consider a surrogate @Id on the join entity if OpenAPI consumers choke on composite keys.