More ProjectReference API documentation

I understand that the implementation of it isn't part of Core MSBuild source code, but it would be very useful to have the MS Build ProjectReference Protocol documentation to include other 'languages', e.g. like CppBuild related information.

Perhaps this is already gathered as input to the Static Graph specification, e.g. for ProjectReferenceTargets?

I looked at references to "_MSBuildProjectReferenceExistent" that use the MSBuild task in the existing Microsoft.CppBuild.targets file.

So, this CppBuild ProjectReference protocol information might include the following targets from CppBuild:
* GetResolvedLinkObjs
* GetResolvedLinkLibs
* GetResolvedXDCMake
* BuiltProjectOutputGroup
* BuiltProjectOutputGroupDependencies
* DebugSymbolsProjectOutputGroup
* DebugSymbolsProjectOutputGroupDependencies

The reason behind this that I am "extending" the CppBuild ProjectReference API to update CLCompile.AdditionalIncludeDirectories with the interface header folder of a referenced project (similar to GetResolvedLinkLibs) and I realized that the CppBuild part of ProjectReference is not (yet) in the Protocol document.

If it would not be part of the core MSBuild documentation, where would be the right place be for (public) documentation on this?