title: Play2 add new field to JsObject
body: <p>Is it possible to add new field to JsObject?</p>
  
  <pre><code>val jsonObj = Json.obj()
  jsonObj.put("field" -&gt; 100) &lt;==== Somthing like this
  </code></pre>
  
  <p>I have a lot of methods that add new fields. How can I dynamically create JsObject?</p>