The only problem I have is the new syntax has trained me to expect a ? when null is possible, and null is not allowed if ? is missing, but in older libraries no

The only problem I have is the new syntax has trained me to expect a ? when null is possible, and null is not allowed if ? is missing, but in older libraries not yet updated to C# 8 Nullable Types, not having a ? means null is allowed. So reading the syntax in my IDE is a lot harder as sometimes an un-annotated type means null is allowed and sometimes not. I wish in cross-over projects there was the option to use ! to say null shouldn’t be allowed, thus visually and temporarily distinguishing new from old code, and to that end, the ! could be inserted as an overlay by my IDE, I suppose... Maybe I should try to write an IDE plug-in for this, or have a look for one.