<x:Array
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
  xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
  xmlns:coll="clr-namespace:System.Collections;assembly=mscorlib"
  xmlns:nuget="clr-namespace:NuGet.PackageManagement.UI"
  xmlns:sys="clr-namespace:System;assembly=mscorlib"
  Type="{x:Type nuget:PackageItemListViewModel}"
  >
  <nuget:PackageItemListViewModel
    Id="TestPackage1"
    />
  <nuget:PackageItemListViewModel
    Id="TestPackage2"
    />
</x:Array>