Missing set-cookie header on POST in Spring MVC 3.1 - spring-mvc

Question

Cookies added to the HttpServletResponse during an $.ajax POST call do not appear in the response header (there is no set-cookie). The same code does function properly during GET requests.
I have the following code in an interceptor postHandle:
public void postHandle(HttpServletRequest request, HttpServletResponse response,
Object handler, ModelAndView modelAndView) throws Exception {
.
.
Cookie cookie = new Cookie(User.USER_KEY, userAsJson);
LOGGER.info("Cookie json is: " + userAsJson);
cookie.setPath("/");
response.addCookie(cookie);
LOGGER.info("Header names: " + response.getHeaderNames());
LOGGER.info("Set-cookie header(s): " + response.getHeaders("Set-Cookie"));
}
I'm seeing this issue when returning from a request to this mapping:
#RequestMapping(value = "/api/user/wait", method = RequestMethod.POST)
#ResponseBody
public User waitingApi(HttpSession session) {
Ajax call parameters:
var ajaxMessage = {
url : '/api/user/wait',
type : 'POST',
success : waitCallback,
error : waitErrorCallback
};
On a GET I see the following in my logs:
Cookie json is: { my valid json object }
Header names: [Set-Cookie]
Set-cookie header(s): [user="{ my valid json object }"; Version=1;
Path=/]
On a POST I see the following in my logs:
Cookie json is: { my valid json object }
Header names: [Content-Type, Transfer-Encoding, Date, Server]
Set-cookie header(s): [] <--- this is empty, not redacted

Answer 1

After much time spent with google, I found this post:
http://mjremijan.blogspot.ca/2012/06/spring-not-setting-cookie-on-ajax.html
Is short, the postHandle interceptor doesn't do anything when the request hits an operation which has the annotation #ResponseBody. You can set the cookie inside the operation method by adding the response object to the operation parameters and calling addCookie inside the operation.

Answer 2

In both postHandle and afterCompletion methods it check whether the response is committed or not. Both scenarios are too late to add a cookie.
Set the cookie inside the preHandle and you good to go.