Force project references to be included in netstandard nuget package
You can control where assemblies are deployed in the nuget package using an item in an itemgroup, similar to this:
<ItemGroup>
<None Include="!!path_to_assembly!!">
<PackagePath>lib\net462</PackagePath>
<Pack>true</Pack>
<Visible>false</Visible>
</None>
</ItemGroup>
That should include the specified assembly in the package.
You can add the following target to your .csproj:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFrameworks>netstandard2.0;net47</TargetFrameworks>
<TargetsForTfmSpecificBuildOutput>$(TargetsForTfmSpecificBuildOutput);CopyProjectReferencesToPackage</TargetsForTfmSpecificBuildOutput>
</PropertyGroup>
<ItemGroup>
<ProjectReference Include="..\ClassLibrary2\ClassLibrary2.csproj" PrivateAssets="all" />
<ProjectReference Include="..\ClassLibrary3\ClassLibrary3.csproj" Condition="'$(TargetFramework)' == 'net47'" PrivateAssets="all" />
</ItemGroup>
<Target Name="CopyProjectReferencesToPackage" DependsOnTargets="ResolveReferences">
<ItemGroup>
<BuildOutputInPackage Include="@(ReferenceCopyLocalPaths->WithMetadataValue('ReferenceSourceTarget', 'ProjectReference'))" />
</ItemGroup>
</Target>
</Project>
Source 1
Source 2
Reference: Advanced extension points to create customized package