Is it possible to have spring controller directly map a URI to entity?

Question

I use the framework Spring Data Rest for my API end points and controller.

I want to take in an URI to an entity and have spring convert it automatically

For many years the way I've been doing it this way

@PostMapping(value = "/sendEmail")
@ResponseStatus(HttpStatus.OK)
    public ResponseEntity<Void> submit(@RequestParam String uri, String anotherThing) throws Exception {
    convert(uri);   //manual conversion done by me using UriToEntityConverter
}

Is there a way for spring to just do this? I've read something about using Resources but I've tried different ways none work

@PostMapping(value = "/sendEmail")
    @ResponseStatus(HttpStatus.OK)
    public ResponseEntity<Void> submit(@RequestBody Resource<DTO> dto) throws Exception {
    //exception cannot create resource
}

@Getter
@Setter
public class DTO {
   String anotherThing;
   Entity entity;
}

Desired JSON input

{
   "entity":"https://localhost:8080/api/v1/books/226",
    "anotherThing": "hi"
}