Multiple content types for POST does not work

#%RAML 1.0
title: API with Types
types:
  User: !include user.schema

/users/{id}:
  post:
    description: Post user in XML format
    body:
      application/xml:
        type: string
      application/json:
        type: User
    responses:
      201:
        description: OK
        body:
          application/xml:
            type: string
            example: "<x>y</x>"

curl -HX-Okapi-Tenant:testlib -HContent-Type:application/xml -XPOST -d'<xml/>' http://localhost:8081/users/1
Content-type header must be ["application/json"] but it is "application/xml"