Links are wrongly serialized when MappingJacksonValue is used as a return type [DATAREST-1179]

Sam Kruglov opened DATAREST-1179 and commented

Method in @RepositoryRestController:

@GetMapping(value = "users/{id}", params = "fields")
public ResponseEntity<MappingJacksonValue> getUser(@PathVariable("id") Long id,
                                                   @RequestParam(value = "fields") String fields,
                                                   HttpServletRequest request) {
    
    Resource<User> userResource = new Resource<>(userRepository.findOne(id));
    
    userResource.add(new Link(request.getRequestURL() + "?fields=" + fields).withSelfRel());
    userResource.add(links.linkToSingleResource(userResource.getContent()).withRel("user"));
    userResource.add(links.linkToSingleResource(userResource.getContent().getGroup()).withRel("group"));
    
    MappingJacksonValue wrapper = new MappingJacksonValue(userResource);
    
    wrapper.setFilters(new SimpleFilterProvider()
                               .addFilter("userFilter",
                                          SimpleBeanPropertyFilter.filterOutAllExcept(fields.split(","))));
    return ResponseEntity.ok(wrapper);
}

Accessing GET users/1?fields=firstName

{
    "firstName": "John",
    "links": [
        {
            "rel": "self",
            "href": "http://localhost:8080/users/1?fields=firstName"
        },
        {
            "rel": "user",
            "href": "http://localhost:8080/users/1{?projection}"
        },
        {
            "rel": "group",
            "href": "http://localhost:8080/groups/1"
        }
    ]
}

Expected _links instead of *links * and href to be inside rel

Affects: 2.6.9 (Ingalls SR9)