Question: Why are transitive dependencies not resolved for a custom task in a NuGet package?

I have a custom MSBuild task that is contained in a NuGet package. The build directory of the package has a target file that uses the task so the user only has to add a package reference for the MSBuild task to execute.

That part works fine. However, package dependencies for my custom task are not being resolved. I have been working on this for several days and cannot figure it out. The attached file is a concise example. Any help would be greatly appreciated.

[MSBuildTaskSample.zip](https://github.com/Microsoft/msbuild/files/2130872/MSBuildTaskSample.zip)