title: RestAssured content-type application/json not being recognised by service
body: <p>I have a service, which I can access with the following jQuery code (from google chrome with --disable-web-security)</p>
  
  <pre><code>$.ajax({
      type: 'POST',
      url: "http://10.30.1.2:9234/myapp/v6/token/generate",
      headers: {
          "Content-Type":"application/json",
          "Accept":"application/json"
      },
      data: JSON.stringify({ 
        "staffId" : "13254",
        "password" : "JustADummyPassword"
      })
  }).done(function(data) { 
      console.log(data);
  });
  
  $.ajax({
      type: 'GET',
      url: "http://10.30.1.2:9234/myapp/v6/user/appl/Firstname/Lastname/email@address.com/1998-01-01",
      headers: {
          "Content-Type":"application/json",
          "Accept":"application/json"
      }
  }).done(function(data) { 
      console.log(data);
  });
  </code></pre>
  
  <p>The first call sets a cookie, which is required for the second call to authenticate. This works fine, and both requests return expected results.</p>
  
  <p>I am trying to set up automated testing for the service, and have this written in JAVA, using RestAssured.</p>
  
  <pre><code>public class UserApplication {
      public static Map&lt;String, String&gt; authCookies = null;
      public static String JSESSIONID = null;
      public static void main(String[] args) {
          Response resp = hello();
          resp = apiUserApplication();
      }
  
      public static Response apiUserApplication() {
          String userAppl = "http://10.30.1.2:9234/myapp/v6/user/appl/Firstname/Lastname/email@address.com/1998-01-01";
  
          Response response = RestAssured.given()
                  .cookie("JSESSIONID", JSESSIONID).and()
                  .header("Accept", "application/json").and()
                  .header("Content-Type", "application/json").and()
                  .when().get(userAppl);
  
          return response;
      }
  
      public static Response hello() {
          String helloUrl = "http://10.30.1.2:9234/myapp/v6/hello";
  
          Response response = RestAssured.given().cookies(authCookies)
                  .contentType("application/json").when().get(helloUrl);
  
          return response;
      }
  }
  </code></pre>
  
  <p>The first call (hello) works fine, and returns 200 code, and gets a valid token for use in the second call. The error I am getting from the second call with a 400 status code is...</p>
  
  <pre><code>{"errors":["Content type 'null' not supported"]}
  </code></pre>