title: UWP Brokered Windows Runtime Component Build error
body: <p>I Created a simple .Net class library using VS2017 and windows 10 and changed the output type to winmdobj as stated in this msdn guide:
  <a href="https://docs.microsoft.com/en-us/windows/uwp/winrt-components/brokered-windows-runtime-components-for-side-loaded-windows-store-apps" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/windows/uwp/winrt-components/brokered-windows-runtime-components-for-side-loaded-windows-store-apps</a> 
  but after that I build the code and it errors with:</p>
  
  <p>Platform Attribute 'Windows.Foundation.Metadata.ActivatableAttribute' is either defined in an assembly that is not referenced or does not have the expected constructor. Please ensure that your assembly references include the .NET Framework and Windows Runtime platform assemblies, such as System.Runtime.dll and Windows.winmd.  </p>
  
  <p>I added a reference to System.Runtime.dll and  Window.winmd but still giving me the same error</p>
  
  <p>Am I using the wrong references? Any help please?</p>