Custom bearer authorize filter for ASP.NET Core 5.0

BearerAuthorizeFilter.cs

public sealed class BearerAuthorizeFilter : IAsyncAuthorizationFilter
{
    public async Task OnAuthorizationAsync(AuthorizationFilterContext context)
    {
        if (context?.HttpContext?.Request?.Headers == null) throw new ArgumentNullException(nameof(context));

        if (!context.HttpContext.Request.Headers.ContainsKey("Authorization"))
            context.Result = CreateUnauthorized();

        var policyEvaluator = context.HttpContext.RequestServices.GetRequiredService<IPolicyEvaluator>();
        var authenticateResult = await policyEvaluator.AuthenticateAsync(default, context.HttpContext);
        var authorizeResult = await policyEvaluator.AuthorizeAsync(default, authenticateResult, context.HttpContext, context);

        if (authorizeResult.Challenged)
        {
            context.Result = CreateUnauthorized();
            return;
        }

        context.HttpContext.User = authenticateResult.Principal;

        static IActionResult CreateUnauthorized() => new UnauthorizedObjectResult(new ErrorMessage("Unauthorized", 401));
    }
}