title: Nuget package doesn't copy contentFiles specified in .nuspec
body: <p>I have a custom nuspec file for a c# project. In this example, the project is supposed to produce a nuget package which has an exe and a folder with some extra content in it.</p>
  <pre><code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
  &lt;package xmlns=&quot;http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd&quot;&gt;
      &lt;metadata&gt;
          &lt;id&gt;$id$&lt;/id&gt;
          &lt;version&gt;$version$&lt;/version&gt;
          &lt;authors&gt;$authors$&lt;/authors&gt;
          &lt;description&gt;$description$&lt;/description&gt;
          &lt;contentFiles&gt;
              &lt;files include=&quot;Program.exe&quot; buildAction=&quot;Content&quot; copyToOutput=&quot;true&quot; /&gt;
              &lt;files include=&quot;Folder/**/*&quot; buildAction=&quot;Content&quot; copyToOutput=&quot;true&quot; /&gt;
          &lt;/contentFiles&gt;
      &lt;/metadata&gt;
  
  
      &lt;files&gt;
          &lt;file src=&quot;src\Program.exe&quot; target=&quot;contentFiles&quot;/&gt;
          &lt;file src=&quot;src\Folder\**\*&quot; target=&quot;contentFiles\Folder&quot;/&gt;
      &lt;/files&gt;
  &lt;/package&gt;
  </code></pre>
  <p>When I inspect the .nupkg, the files are all there inside of a contentFiles folder. However when I try and consume the package with a package reference</p>
  <pre><code>&lt;PackageReference Include=&quot;MyPackage&quot; Version=&quot;1.0.0&quot; /&gt;
  </code></pre>
  <p>..the files don't actually end up in the output folder. It's probably a small issue but I can't seem to be able to find an answer. Any hints would be great.</p>