See #708 (comment), extra files in sdk/<version>/Sdks/NuGet.Build.Tasks.Pack/CoreCLR:

• NuGet.Commands.dll
• NuGet.Common.dll
• NuGet.Configuration.dll
• NuGet.Credentials.dll
• NuGet.DependencyResolver.Core.dll
• NuGet.Frameworks.dll
• NuGet.LibraryModel.dll
• NuGet.Packaging.Core.dll
• NuGet.Packaging.dll
• NuGet.ProjectModel.dll
• NuGet.Protocol.dll
• NuGet.Versioning.dll

Note that the sibling Desktop folder is of interest since we now build net46 assets for NuGet but probably not strictly required.