title: how can an object be not json serializable?
body: <pre><code>    private FbDataToServer generateFbDataToServer(
              GraphObject graphObject) {
              Gson gson = new Gson();
              FbDataToServer fbDataToServer = new FbDataToServer();
    ֿ         fbDataToServer.fbJson = gson.toJson(graphObject
              .getInnerJSONObject());
  </code></pre>
  
  <p>Everytime I try to parse FB graphObject object to Json -</p>
  
  <p>an error is thrown.</p>
  
  <p>How can it be? how can an object be not json serializable? </p>
  
  <p>The error said the object is not serializable.
  I'll try to get reproduce the error again.</p>