.targets/.props in build/ folder are not added to a (non-C#) CPS-based project upon package install

I have a CPS-based project type for a custom Language (not C# or VB). This project type reports the AssemblyReferences, DeclaredSourceItems, and UserSourceItems capabilities. I also created a NuGet package that just contains minimal .targets/.props in the build/ folder.

If I install this NuGet package to a C# Class Library project, the .targets/.props are successfully added to the .csproj.

However, if I install this NuGet package to my CPS project type, no .targets/.props are added to the project file (.sfproj).

I am using NuGet 3.3.0 both to create my package, and to install it.