title: spring oauth obtain user details from token
body: <p>i want to use spring and oauth and so far it seemed to work.
  now i added a zuul proxy that is configured like that:</p>
  
  <pre><code>spring:
    oauth2:
      sso:
        home:
          secure: false
          path: /,/**/*.html
      client: 
        accessTokenUri: http://${authserver.hostname}:${authserver.port}/${authserver.contextPath}/oauth/token
        userAuthorizationUri: http://${authserver.hostname}:${authserver.port}/${authserver.contextPath}/oauth/authorize
        clientId: webapp
        clientSecret: secret
      resource:
        id: apis
        userInfoUri: http://${authserver.hostname}:${authserver.port}/${authserver.contextPath}/rest/me
        preferTokenInfo: false
  </code></pre>
  
  <p>whenever i try to access an resource server it tries to verify my authentication but my authserver endpoint seems to return text/html instead of json.</p>
  
  <pre><code> Created GET request for "http://localhost:8091/userauth/rest/me"
  2015-11-24 14:07:12.275 DEBUG 3601 --- [nio-8080-exec-3] o.s.s.oauth2.client.OAuth2RestTemplate   : Setting request Accept header to  [application/json, application/*+json]
  2015-11-24 14:07:12.287 DEBUG 3601 --- [nio-8080-exec-3] o.s.s.oauth2.client.OAuth2RestTemplate   : GET request for "http://localhost:8091/userauth/rest/me" resulted in 200 (OK)
  2015-11-24 14:07:12.288  INFO 3601 --- [nio-8080-exec-3] o.s.c.s.o.r.UserInfoTokenServices        : Could not fetch user details: class org.springframework.web.client.RestClientException, Could not extract response: no suitable HttpMessageConverter found for response type [interface java.util.Map] and content type [text/html;charset=UTF-8]
  </code></pre>
  
  <p>i already forced json and when accessing auth server directly via curl i get json formatted principal.</p>
  
  <pre><code>@RequestMapping(value="/me", produces = "application/json")
  public Principal getCurrentLoggedinUser(Principal user){
      return user;
  }
  </code></pre>
  
  <p>any ideas how to send json to my zuul proxy so it can verify my authentication?</p>