There are following lines in the StreamsExamples.csproj file:

<Reference Include="System.Collections.Immutable, Version=1.1.36.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
  <HintPath>..\..\..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll</HintPath>
  <Private>True</Private>
</Reference>

However, the corresponded packages.config doesn't include reference to System.Collections.Immutable. Also there is no reference to System.Collections.Immutable.1.1.36 in other projects (only version 1.3.1 is used). Thus, we don't have the ..\..\..\packages\System.Collections.Immutable.1.1.36\lib\portable-net45+win8+wp8+wpa81\System.Collections.Immutable.dll file after NuGet restore.