Spring 4.1.1 RELEASE和@ResponseBody返回HTTP 406

I am using @ResponseBody to return Json object in Spring MVC. It works as expected on release 4.0.7 and 3.2.11, but it returns HTTP status 406 when I try to use the latest Spring release 4.1.1(as of 10/16) with no any other configuration changes. Is this considered a bug or the 4.1.1 requires different configuration?I am using @ResponseBody to return Json object