title: transform itemgroup into another itemgroup with wildcards
body: <p>I have a list of directories defined inside a target:</p>
  
  <pre><code>&lt;Target&gt;
    &lt;ItemGroup&gt;
      &lt;FooDirs Include="Foo\Dir1" /&gt;
      &lt;FooDirs Include="Foo\Dir2" /&gt;
    &lt;/ItemGroup&gt;
  &lt;Target&gt;
  </code></pre>
  
  <p>Now I want to create list of all files inside <code>@(FooDirs)</code>:</p>
  
  <pre><code>&lt;ItemGroup&gt;
    &lt;FooFiles Include="@(FooDirs -&gt; '%(Identity)\**\*')" /&gt;
  &lt;/ItemGroup&gt;
  </code></pre>
  
  <p>Which unfortunately does not work, resulting list contains literal strings: <code>"Foo\Dir1\**\*;Foo\Dir2\**\*"</code>.
  However, if I use deprecated <code>&lt;CreateItem&gt;</code> task it works fine:</p>
  
  <pre><code>&lt;CreateItem Include="@(FooDirs -&gt; '%(Identity)\**\*')"&gt;
    &lt;Output TaskParameter="Include" ItemName="FooFiles" /&gt;
  &lt;/CreateItem&gt;
  </code></pre>
  
  <p>Is this a bug or am I missing something ?</p>