Force project references to be included in netstandard nuget package

Question

I have a netstandard project which includes two project references. Visual studio 2017 is being used to build the nukpg. When the project is built the produced nupkg only contains the assembly produced by that project and lists the two project references as nuget dependencies. Is there a way to force the packaging to include those assemblies as lib files?

csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net462</TargetFramework>
    <RootNamespace>Verifier.Observations.DevOps.Health</RootNamespace>
    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
    <VersionPrefix>1.0.1</VersionPrefix>
  </PropertyGroup>

  <ItemGroup>
    <ProjectReference Include="..\Verifier.Observations.Aspects\Verifier.Observations.Aspects.csproj" />
    <ProjectReference Include="..\Verifier.Observations\Verifier.Observations.csproj" />
  </ItemGroup>

  <ItemGroup>
    <Reference Include="System.ComponentModel.Composition"/>
    <Reference Include="System.Net.Http" />
  </ItemGroup>

</Project>

Update Based upon feedback from @alexgiondea-msft the package is now created as desired using the following

csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <VersionPrefix>1.0.1</VersionPrefix>
    <TargetFramework>net462</TargetFramework>
    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
    <NuspecFile>Verifier.Observations.DevOps.Health.Nuspec</NuspecFile>
   <NuspecProperties>version=$(VersionPrefix);id=$(MSBuildProjectName);author=$(Authors);copy=$(Copyright);iconUrl=$(PackageIconUrl)</NuspecProperties>
  </PropertyGroup>
  <ItemGroup>
    <ProjectReference Include="..\Verifier.Observations.Aspects\Verifier.Observations.Aspects.csproj" />
    <ProjectReference Include="..\Verifier.Observations\Verifier.Observations.csproj" />
  </ItemGroup>
  <ItemGroup>
    <Reference Include="System.ComponentModel.Composition" />
    <Reference Include="System.Net.Http" />
  </ItemGroup>
</Project>

nuspec

<package >
  <metadata>
    <id>$id$</id>
    <version>$version$</version>
    <title>$title$</title>
    <authors>$author$</authors>
    <owners>$author$</owners>
    <iconUrl>$iconUrl$</iconUrl>
    <requireLicenseAcceptance>false</requireLicenseAcceptance>
    <description>Inspect automation service to ensure it is up and operational</description>
    <releaseNotes></releaseNotes>
    <copyright>$copy$</copyright>
    <tags>verifier-observation-plugin automation</tags>
    <dependencies>
      <group targetFramework="net462" />
    </dependencies>
    <references>
      <group targetFramework="net462">
        <reference file="Verifier.Observations.DevOps.Automation.dll" />
      </group>
    </references>
  </metadata>
  <files>
    <file src="bin\*\net462\*.dll" target="lib\net462" />
    <file src="bin\*\net462\*.pdb" target="lib\net462" />
  </files>
</package>

Answer 1

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