Directory.Build.targets

<Project>
    <Target Name="UseExplicitPackageVersions" BeforeTargets="GenerateNuspec">
    <ItemGroup>
      <_ProjectReferenceWithExplicitPackageVersion 
        Include="@(ProjectReference->'%(FullPath)')"
        Condition="'%(ProjectReference.PackageVersion)' != ''" />

      <_ProjectReferenceWithExactPackageVersion 
        Include="@(ProjectReference->'%(FullPath)')"
        Condition="'%(ProjectReference.ExactVersion)' == 'true'" />

      <_ProjectReferenceWithReassignedVersion 
        Include="@(_ProjectReferencesWithVersions)"
        Condition="'%(Identity)' != '' And '@(_ProjectReferencesWithVersions)' == '@(_ProjectReferenceWithExplicitPackageVersion)'">

        <ProjectVersion>@(_ProjectReferenceWithExplicitPackageVersion->'%(PackageVersion)')</ProjectVersion>
      </_ProjectReferenceWithReassignedVersion>

      <_ProjectReferenceWithReassignedVersion 
        Include="@(_ProjectReferencesWithVersions)"
        Condition="'%(Identity)' != '' And '@(_ProjectReferencesWithVersions)' == '@(_ProjectReferenceWithExactPackageVersion)'">

        <ProjectVersion>[@(_ProjectReferencesWithVersions->'%(ProjectVersion)')]</ProjectVersion>
      </_ProjectReferenceWithReassignedVersion>

      <_ProjectReferencesWithVersions Remove="@(_ProjectReferenceWithReassignedVersion)" />
      <_ProjectReferencesWithVersions Include="@(_ProjectReferenceWithReassignedVersion)" />
    </ItemGroup>
  </Target>
</Project>