Updated PeopleController with JsonNullableUtils

PeopleController.java

@RestController
@RequestMapping("/api/people")
public class PeopleController {
    ...

    @PatchMapping("{id}")
    public ResponseEntity<Void> updatePerson(@PathVariable("id") long id,
                                             @Valid @RequestBody PersonUpdateDto personUpdateDto) {
        Optional<Person> personOptional = peopleRepository.getById(id);
        if (!personOptional.isPresent()) {
            return ResponseEntity.notFound().build();
        }

        Person person = personOptional.get();
        JsonNullableUtils.changeIfPresent(personUpdateDto.getFirstName(), person::setFirstName);
        JsonNullableUtils.changeIfPresent(personUpdateDto.getLastName(), person::setLastName);
        JsonNullableUtils.changeIfPresent(personUpdateDto.getBirthday(), person::setBirthday);
        JsonNullableUtils.changeIfPresent(personUpdateDto.getBio(), person::setBio);
        JsonNullableUtils.changeIfPresent(personUpdateDto.getImageUrl(), person::setImageUrl);

        peopleRepository.save(person);

        return ResponseEntity.noContent().build();
    }
}