title: How do I get Jxls to generate multiple collections
body: <p>here is the problem I am faced with: Nested Collections.</p>
  
  <p>I have an ArrayList (the top level collection) of class . Within each <strong>Subject</strong> I have another ArrayList of type <strong>Group</strong>. The finally I have within each group an ArrayList of <strong>Students</strong>.</p>
  
  <p>I am trying to get the format of my excel file to look like this.</p>
  
  <pre><code>**SUBJECT 1**
  GROUP 1
   Students
  
  GROUP 2
   Students
  
  **SUBJECT 2**
  </code></pre>
  
  <p>So I'm trying to nest these collections. The trouble is that My final excel file doesn't seem to show all of the data. And I know why. At my top level collection: <strong>Subjects</strong> I have the code:</p>
  
  <p><code>${data.subjects.groups.letter}//:4</code></p>
  
  <p>The //:4 at the end deceives it because there are going to be multiple groups.
  Please please please please, how can I nest multiple collections please?</p>