title: How to bind a list of item in CollectionViewSource?
body: <p>I'm stuck in this problem for days. Never found a solution. So I've a list of items called <code>Country</code>, in this list I've also another list of items called <code>League</code>. I've create a CollectionViewSource for organize all of this in nation name and league name but I can't bind all the leagues name:</p>
  
  <pre><code>&lt;CollectionViewSource Source="{Binding Country}" x:Key="GroupedItems"&gt;
              &lt;CollectionViewSource.GroupDescriptions&gt;
                  &lt;PropertyGroupDescription PropertyName="Name" /&gt;
                  &lt;PropertyGroupDescription PropertyName="League.Name" /&gt;
              &lt;/CollectionViewSource.GroupDescriptions&gt;
  &lt;/CollectionViewSource&gt;
  </code></pre>
  
  <p>I should write: <code>&lt;PropertyGroupDescription PropertyName="League[0].Name" /&gt;</code></p>
  
  <p>but this only will bind the first item of the league list. Any solution?</p>
  
  <p><strong>PRACTICE EXAMPLE</strong></p>
  
  <p>suppose that there are two countries (Italy, England), Italy country have two leagues (Serie A and Serie B) and England have (Premiere League) only.
  Serie A and Serie B contains in total 3 matches, 2 in Serie A and 1 in Serie B. In premiere League there are 4 matches.
  In the ListView organization as my other topic that <a href="https://stackoverflow.com/questions/38549818/cannot-bind-list-of-items-in-gridview-column">you can see here</a>, in the UI should be displayed this structure:</p>
  
  <pre><code>ITALY
      SERIE A
            INTER
            MILAN
      SERIE B
            JUVENTUS
  ENGLAND
      PREMIERE LEAGUE
            LEICESTER
            MANCHESTER UNITED
            MANCHESTER CITY
            LIVERPOOL
  </code></pre>
  
  <p>Now Italy and england are disposed into groupstyle as serie a, serie b and premiere league, with an expander (as you can see in my other question) there is the matches for each leagues.
  The problem's that in the CollectionViewSource I cannot display the name of the league 'cause the leagues are inside a list, the same problem is for the matches, that is a list available in league, data structure:</p>
  
  <pre><code>Nations-&gt;Leagues-&gt;Matches
  </code></pre>