title: Jasper use json response to fill page header
body: <p>I have the following json generated by a endpoint:</p>
  
  <pre><code>{
      "data":
      {
          "id":"2",
          "type":"mytype",
          "attributes":
          {
              "header":
              {
                  "name": "Name",
                  "code": "Code"
              },
              "dataset": [
                  {}]
          },
          "links":{"self":"http://localhost:1025/"}
      }
  }
  </code></pre>
  
  <p>I use a JSONAdapter and query the "dataset" attribute do fill my report. It works fine.
  But i want to add a page header that uses the "headers" part of the json response.</p>
  
  <p>Is there a way of doing that without have the pass those informations via parameters?</p>