title: Exporting interface from class .NET core
body: <p>I have some code that was working Okay using .NET but when the code was ported to start using .NET core i'm no longer able to export the interface below with an the error</p>
  
  <p><strong>The type or namespace name 'ExportAttribute' could not be found</strong></p>
  
  <pre><code>// Interface.cs
  public interface IModule {
      string name {
          get;
      }
  }
  
  // TestModule.cs
  [Export ( typeof ( IModule ) )]
  public class TestModule : IModule {
  }
  </code></pre>
  
  <p>What is wrong with the Export line? Is that not allowed in .NET core?</p>