Directory.Build.targets

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <MSBuildWarningsAsErrors>$(MSBuildWarningsAsErrors);PO1001</MSBuildWarningsAsErrors>
  </PropertyGroup>

  <Target Name="BlockUnwantedDependencies" BeforeTargets="PrepareForBuild">
    <ItemGroup>
      <UnwantedPackages Include="@(PackageReference)"
                        Condition="'%(PackageReference.Version)' != '' and
                                        $([System.Text.RegularExpressions.Regex]::IsMatch('%(PackageReference.Version)', '^(0\.\d+\.\d+.*|.*-.*)'))" />
    </ItemGroup>

    <PropertyGroup>
      <_WarningMessage>Build blocked: Prerelease or unstable NuGet package</_WarningMessage>
    </PropertyGroup>

    <Warning File="$(MSBuildProjectFullPath)"
             Code="PO1001"
             Text="$(_WarningMessage): %(UnwantedPackages.Identity) (%(UnwantedPackages.Version))"
             Condition="'@(UnwantedPackages)' != ''" />
  </Target>
</Project>