referenceAssemblies.props

<Project>
  <PropertyGroup>
    <AdditionalBuildTargetFrameworks Condition="'$(BuildAllProjects)' == 'true'">$(AdditionalBuildTargetFrameworks);netstandard2.0;netstandard2.1</AdditionalBuildTargetFrameworks>    

    <!-- disable warnings about unused fields -->
    <NoWarn>$(NoWarn);CS0169;CS0649;CS8618</NoWarn>

    <!-- disable CS8597 because we throw null on reference assemblies. -->
    <NoWarn>$(NoWarn);CS8597</NoWarn>

    <!-- We base calls from constructors with null literals. -->
    <NoWarn>$(NoWarn);CS8625</NoWarn>

    <!-- We dont need to add null annotation within the ref for explicit interface methods. -->
    <NoWarn>$(NoWarn);CS8617</NoWarn>
  </PropertyGroup>

  <ItemGroup>
    <!-- All reference assemblies should have the 0x70 flag which prevents them from loading
         and the ReferenceAssemblyAttribute. -->
    <AssemblyInfoLines Include="[assembly:System.Runtime.CompilerServices.ReferenceAssembly]" />
    <AssemblyInfoLines Include="[assembly:System.Reflection.AssemblyFlags((System.Reflection.AssemblyNameFlags)0x70)]" />
  </ItemGroup>
</Project>