According to https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/member-access-operators#null-conditional-operators--and- https://docs.m

According to https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/member-access-operators#null-conditional-operators--and- https://docs.microsoft.com/en-us/dotnet/csharp/language-refe..., ?. was only added to C# 6.0, in 2015. Groovy had ?. in at least 2005. Then there were CoffeeScript, Kotlin, Swift and a bunch of others in the meantime. Not that it matters :)