sent from client (potential N+1 problem) Fetch books: Fetch authors: GET /books [ { "id": 122, "title": "Modern Java", "publicationYear": 2021, "coverUrl": "https://...", "authorId": 344, }, { "id": 123, "title": "Spring in Action", "publicationYear": 2020, "coverUrl": "https://...", "authorId": 345, } ] GET /authors/344 { "id": 344, "name": "John Smith", "avatarUrl": "https://..." } GET /authors/345 { "id": 344, "name": "John Smith", "avatarUrl": "https://..." }