Possible null reference argument warning?

[scottdorman]

Given the following code

public class AuthConfiguration
{
   public string? RedirectPath { get; set; }
   public IEnumerable<string>? Scopes { get; set; }
}

internal static class AuthConfigurationValidator
{
   public static void Validate(AuthConfiguration configuration)
   {
      Requires.NotNullOrWhiteSpace(configuration.RedirectPath, nameof(configuration.RedirectPath));
      Requires.NotNullOrEmpty(configuration.Scopes, nameof(configuration.Scopes));
   }
}

Both calls to Requires generate a compiler warning:

Warning CS8604  Possible null reference argument for parameter 'value' in 'void Requires.NotNullOrWhiteSpace(string value, string? parameterName)'.
Warning CS8604  Possible null reference argument for parameter 'values' in 'void Requires.NotNullOrEmpty<string>(IEnumerable<string> values, string? parameterName)'.

If the signatures for those methods are changed so that the values parameter is marked as nullable, then this warning should go away.

Is this a valid scenario or am I missing something about how the nullability rules work?

[AArnott]

Interesting topic, @scottdorman. Please review https://github.com/microsoft/vs-validation/pull/37 (expand the resolved discussions there) to see why we settled on this.