controllerLayer.java

protected final Function<UserNotPresentError, ResponseEntity<?>> userFacadeErrorHandler =
    userNotPresentError -> ResponseEntity.status(HttpStatus.UNAUTHORIZED).build();

protected final Function<Either<ItemsError, ?>, ResponseEntity> resultHandler = serviceResult -> serviceResult.fold(
    itemsError -> handleItemsError(itemsError),
    successValue -> Match(successValue).of(
        Case($(), ()  -> ResponseEntity.ok(successValue).build())
    )
);

protected ResponseEntity handleItemsError(ItemsError itemsError) {
  return Match(itemsError).of(
    Case($(instanceOf(DbError.class)),              (e) -> ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(e.reason)),
    Case($(instanceOf(ItemsProcessingError.class)), (e) -> ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(e.reason)),
  );
}

@GetMapping("/some-items-endpoing")
ResponseEntity controllerMethod() {
   authenticatedItemsFacade.itemsFn().fold(userFacadeErrorHandler, resultHandler);
}