ProfileController.kt

@RestController
@RequestMapping(path = ["/profiles"])
class ProfileController(private val createProfile: CreateProfile) {

    /**
     * simulating an authentication context by passing the userId in a header,
     *  no need to set up all the security frameworks for this demo, but never do that in production !!!
     */
    @PostMapping
    fun createProfile(@RequestHeader("User-Id") userId: String, @RequestBody preferences: Preferences): ResponseEntity<Profile> {
        val profile = createProfile.forUserWithPreferences(userId, preferences.toDomainObject()).toResource()
        val location = linkTo(this::class.java).slash(profile).toUri()
        return ResponseEntity.created(location).body(profile)
    }

    @ExceptionHandler(ProfileAlreadyExistsException::class)
    fun handleProfileAlreadyExistsException(response: HttpServletResponse, exception: ProfileAlreadyExistsException) {
        response.sendError(SC_CONFLICT, exception.message)
    }
}

RecommendationController.kt

@RestController
@RequestMapping(path = ["/recommendations"])
class RecommendationController(private val recommendTalks: RecommendTalks) {

    @PostMapping
    fun createRecommendation(@RequestHeader("User-Id") user: String): ResponseEntity<Recommendation> {
        val domainRecommendation = recommendTalks to user
        val recommendation = domainRecommendation.toResource()
        val location = linkTo(this::class.java).slash(recommendation).toUri()

        return ResponseEntity.created(location).body(recommendation)
    }

    @ExceptionHandler(ProfileNotFoundException::class)
    fun handleProfileNotFoundException(response: HttpServletResponse, exception: ProfileNotFoundException) {
        response.sendError(HttpServletResponse.SC_BAD_REQUEST, exception.message)
    }
}