Consider making TokenExtensions.UpdateTokenValue()'s tokenValue parameter nullable #62257
Description
Summary
Likely due to an oversight, the tokenValue parameter exposed by the TokenExtensions.UpdateTokenValue() API isn't currently declared as a string?, even though this parameter is expected to be nullable (it's not null-guarded and it updates a dictionary entry for which values are deliberately nullable).
Motivation and goals
Fixing the signature would offer a better indication that the tokenValue parameter is actually nullable.
Risks / unknowns
This change only affects compilation (since nullable references are hints) and has no risk of runtime regression.
Examples
// Currently logs a CS8604 warning as `GetTokenValue()` returns a `string?`.
properties.UpdateTokenValue("refresh_token", result.Properties.GetTokenValue("refresh_token"));