c# devkit environment variables

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Reading other issues c# devkit seems to generally have problems using environment variables which should be fixed. If it can't use env-variables, there should be a possibility to define them in another way e.g. in .vscode/-folder.

Problem:
.csproj with

<ItemGroup>
    <ProjectReference
      Include="$(envvarpath)\somewhere\afolder\SomeProj.csproj" /
</ItemGroup>"

• dotnet build runs
• debug and build with 'Solution Explorer' runs
• stepping into Method-Calls to the referenced project works: the source-file is opened, breakpoint works. But: there is no intellisense, a message pops up:

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