title: Why wont the MVC3 modelbinder parse List<List<int>> with empty List<int>'s in it?
body: <p>I've got a type of <code>List&lt;List&lt;int&gt;&gt;</code> that I'm trying to get the modelbinder in MVC3 to parse and its failing.  My controller takes that type as a parameter and when I send fully populated lists like so, it works. </p>
  
  <p><strong>Valid, properly parsed / bound data</strong></p>
  
  <p><code>[ [ 22, 12, 9 ], [1, 2, 3], [5] ]</code></p>
  
  <p>As soon as I send the same data structure to the controller, but this time with an empty array, it stops parsing the external collection.  Heres some data the binder chokes on:</p>
  
  <p><strong>Valid, improperly parsed / bound data</strong></p>
  
  <p><code>[ [ 4, 5], [], [6, 7] ]</code></p>
  
  <p>That value is bound to a <code>List&lt;List&lt;int&gt;&gt;</code>, but it has a length of 1 and the first item is a <code>List&lt;int&gt;</code> of <code>4, 5</code></p>
  
  <p>So, how can I get the modelbinder to accept a <code>List&lt;List&lt;int&gt;&gt;</code> when some of the <code>List&lt;int&gt;</code>'s are empty lists?  I need the "valid, improperly parsed / bound" data shown above to work.</p>
  
  <p>Whats worse is that there are no binding errors in the <code>ModelState</code>!  </p>
  
  <p>Also this is being sent as JSON to the controller (via <code>application/json</code>), if that matters.  I'd imagine if this is a bug, its likely specific to that json model binder.</p>