406 Not Acceptable for List - REST - spring

Question

I am trying to find a way instead of Wrapper class but I always get 406 Not Acceptable error. I searched online and tried many different ways but couldn't fix it.
#RequestMapping(value = "/users/getlist", headers="Accept=application/xml, application/json", method=RequestMethod.POST)
public #ResponseBody List<Permission> getList(#RequestParam String userEmail) {
List<Permission> permissions = service.getPermissions(userEmail);
return permissions;
}
And
MultiValueMap<String, String> userMap = new LinkedMultiValueMap<String, String>();
userMap.add("userEmail", email_address);
// Prepare acceptable media type
List<MediaType> acceptableMediaTypes = new ArrayList<MediaType>();
acceptableMediaTypes.add(MediaType.APPLICATION_XML);
// Prepare header
HttpHeaders headers = new HttpHeaders();
headers.setAccept(acceptableMediaTypes);
HttpEntity<?> userEntity = new HttpEntity<Object>(userMap, headers);
List<Permission> permissions = restTemplate.postForObject("http://localhost:8080/users/getlist", userEntity, List.class);
I also tried;
List<Permission> permissions = (List<Permission>) restTemplate.postForEntity("http://localhost:8080/users/getlist", userEntity, List.class);
So basically if I use a wrapper class with getter and setter, it works. But i need to create many wrapper classes. Do you have any idea to implement like this?
SOLUTION:
Worked adding no mediatype to the http entity.

Answer 1

I believe that
headers="Accept=application/xml, application/json"
will require that your Accept header actually has the value application/xml, application/json. Your request doesn't.
You add a single acceptable media type.
List<MediaType> acceptableMediaTypes = new ArrayList<MediaType>();
acceptableMediaTypes.add(MediaType.APPLICATION_XML);
That will end up with a request header like
Accept: application/xml
Which won't match the #RequestMapping declared.
Instead, if you want the headers to match either application/xml or application/json, you can do
headers= {"Accept=application/xml", "Accept=application/json"}
or better yet
produces = {"application/xml", "application/json"}