How to validate request parameter if it is not a bean in spring MVC?

Below is a POST end point in my spring MVC REST service. I want to use spring validation frame work to make sure that list I receive is not empty. How do I do it? Do I have to provide wrapper bean to around listOfLongs?

    @RequestMapping(value = "/some/path", method = RequestMethod.POST)
    @ResponseBody
    public Foo bar(@Valid @NotEmpty @RequestBody List<Long> listOfLongs) {

     /*   if (listOfLongs.size() == 0) {
            throw new InvalidRequestException();
        }
     */

        // do some useful work
    }

What should be the Request Body?

1) [123,456,789]
2) { listOfLongs : [123,456,789]}