The "Postman - REST Client" is not suitable for doing post action with setting content-type.You can try to use "Advanced REST client" or others.
Additionally, headers was replace by consumes and produces since Spring 3.1 M2, see https://spring.io/blog/2011/06/13/spring-3-1-m2-spring-mvc-enhancements. And you can directly use produces = MediaType.MULTIPART_FORM_DATA_VALUE
.