.NET – Which system assemblies are annotated for nullable reference types?

I’m trying to find the status of .NET system assemblies regarding the nullable reference types feature of C# 8.

Non-annotated code, or code written with earlier language versions will be treated as "null-oblivious", meaning the compiler won’t generate any warning regarding nullability.

This is really annoying when it comes to using system assemblies from a nullable enabled context, as there’s no way to tell if null-checking is required or not.

Is there any way to check if an assembly is annotated for nullable reference types?
Or is there some official status page about this?

Source: Windows Questions