title: Json Object returning stackoverflow error
body: <p>I have an object which has list of objects</p>
  
  <pre><code>private ArrayList&lt;Lesson&gt; lessons = Lists.newArrayList();
  </code></pre>
  
  <p>Now, Lesson has some other List </p>
  
  <pre><code>private ArrayList&lt;Question&gt; questions = Lists.newArrayList();
  </code></pre>
  
  <p>and when after doing some processing when i try to convert it into Json with</p>
  
  <pre><code>jsonObject = JSONSerializer.toJSON(this.unit, jsonConfig);
  </code></pre>
  
  <p>I get stackoverflow error:</p>
  
  <pre><code>$Exception in thread "main" java.lang.StackOverflowError
   at java.util.ArrayList$Itr.&lt;init&gt;(ArrayList.java:780)
   at java.util.ArrayList$Itr.&lt;init&gt;(ArrayList.java:780) 
   at java.util.ArrayList.iterator(ArrayList.java:774)
  </code></pre>
  
  <p>can anyone tell me where i am going wrong</p>