HATEOAS - problem with position of page links and page details - spring-hateoas

Question

I'm starting to learn HATEOAS. In response, I would like to display the page details first, then the links to the pages and then the resources. Unfortunately, everything is displayed in reverse order. How could I put the data of "_links {}" and "page {}' at the beginning of Json response before the "_embedded {}" data. They always go to the end :(
My REST controller:
#RestController
#RequestMapping(value = "/api")
public class WebController {
private static final int DEFAULT_PAGE_NUMBER = 0;
private static final int DEFAULT_PAGE_SIZE = 5;
#Autowired
private AlbumRepository albumRepository;
#Autowired
private AlbumModelAssembler albumModelAssembler;
#GetMapping("/test")
public ResponseEntity<PagedModel<AlbumModel>> getAllAlbums(
#PageableDefault(page = DEFAULT_PAGE_NUMBER, size = DEFAULT_PAGE_SIZE) Pageable pageable,
PagedResourcesAssembler<AlbumEntity> pagedResourcesAssembler) {
Page<AlbumEntity> albumEntities = albumRepository.findAll(pageable);
Link selfLink = new Link(ServletUriComponentsBuilder.fromCurrentRequest().build().toUriString());
PagedModel<AlbumModel> collModel = pagedResourcesAssembler.toModel(albumEntities, albumModelAssembler,selfLink);
return new ResponseEntity<>(collModel, HttpStatus.OK);
}
}
I get the following response:
{
"_embedded": {
"albums": [
{
"title": "Top Hits Vol 1",
"description": "Top hits vol 1. description",
"releaseDate": "10-03-1981"
},
{
"title": "Top Hits Vol 2",
"description": "Top hits vol 2. description",
"releaseDate": "10-03-1982"
},
{
"title": "Top Hits Vol 3",
"description": "Top hits vol 3. description",
"releaseDate": "10-03-1983"
},
{
"title": "Top Hits Vol 4",
"description": "Top hits vol 4. description",
"releaseDate": "10-03-1984"
},
{
"title": "Top Hits Vol 5",
"description": "Top hits vol 5. description",
"releaseDate": "10-03-1985"
}
]
},
"_links": {
"first": {
"href": "http://localhost:8080/api/test?page=0&size=5"
},
"self": {
"href": "http://localhost:8080/api/test"
},
"next": {
"href": "http://localhost:8080/api/test?page=1&size=5"
},
"last": {
"href": "http://localhost:8080/api/test?page=1&size=5"
}
},
"page": {
"size": 5,
"totalElements": 10,
"totalPages": 2,
"number": 0
}
}

Answer 1

In general, RFC 8259 states the following:
JSON parsing libraries have been observed to differ as to whether or not they make the ordering of object members visible to calling software. Implementations whose behavior does not depend on member ordering will be interoperable in the sense that they will not be affected by these differences.
which does not recommend to depend on a certain given order structure. Certain implementations do i.e use a HashMap internally that is not able to retain the desired order.
If you use Jackson as your de/serialization framework you can use an annotation like
#JsonPropertyOrder({ "id", "title", "artist", "description", "releaseDate" })
public class AlbumEntity {
...
}
to return the data in the desired order on entity classes you want to return. I'm currently though not aware how you can convince Spring to generate a HAL response representation that aligns the elements (i.e. _links, embedded, ...) in the desired order.
However, even if you i.e. invoke an endpoint via curl, that may yield the desired order, and pipe the output to a pretty-printing tool like json_pp on a Mac OS X system, the order is shingled again, as it doesn't respect the given order. The point here is, every part in the chain needs to preserve the order of the JSON document otherwise the ordering of the content can not be guaranteed.