ITokenValidator and TokenValidator mismatched nullability in method signature

[zikhan]

ITokenValidator.ValidateIdentityTokenAsync signature marks clientId as non-nullable, however TokenValidator.ValidateIdentityTokenAsync defines clientid as nullable.

Not a big deal, as there's the (!) workaround. But really just a Quality of Life thing.

[wcabus]

Looking back at the history, the interface should have defined the clientId parameter as nullable as well. I've raised this with the engineering team, thanks for reporting!