title: RestKit 0.20 nested object mapping trouble using API
body: <p>I'm getting the <code>titleForHeaderInSection</code> correctly, where its pulling the <code>leaf</code>.</p>
  
  <p><strong>But getting nothing for <code>themes</code>.</strong></p>
  
  <p><strong>I'm guessing my mapping to <code>themes</code> is not working</strong>, because <code>cellForRowForIndexPath</code> doesn't seem to be getting called when I set breakpoints.  </p>
  
  <p>But obviously I'm not sure and thats why I'm looking for some guidance.  Thanks!</p>
  
  <p><strong>API JSON</strong></p>
  
  <pre><code>{
      "springs": [{
          "name": "baskets",
          "leafs": [{
              "name": "New Season",
              "abbreviation": "nb",
              "themes": [{
                  "name": "Hops",
                  "abbreviation": "HS",
  }          
  </code></pre>
  
  <p><strong>ViewController.h</strong></p>
  
  <pre><code>@property (strong, nonatomic) NSArray *springs;
  @property (strong, nonatomic) NSMutableArray *leafs;
  @property (strong, nonatomic) NSMutableArray *themes;
  </code></pre>