@RestController

public class ExampleController {

    private final PersonRepository personRepository;

​

    // shortened for clarity

​

    @GetMapping("/hello/{lastName}")

    public String hello(@PathVariable final String lastName) {

        Optional<Person> foundPerson = personRepository.findByLastName(lastName);

​

        return foundPerson

             .map(person -> String.format("Hello %s %s!",

                     person.getFirstName(),

                     person.getLastName()))

             .orElse(String.format("Who is this '%s' you're talking about?",

                     lastName));

    }

}