app.Use(async (context, next) =>
{
    var connectionFeature = context.Features.GetRequiredFeature<IHttpConnectionFeature>();
    var httpSysPropFeature = context.Features.GetRequiredFeature<IHttpSysRequestPropertyFeature>();

    // first time invocation to find out required size
    var success = httpSysPropFeature.TryGetTlsClientHello(Array.Empty<byte>(), out var bytesReturned);
    Debug.Assert(!success);
    Debug.Assert(bytesReturned > 0);

    // rent with enough memory span and invoke
    var bytes = ArrayPool<byte>.Shared.Rent(bytesReturned);
    success = httpSysPropFeature.TryGetTlsClientHello(bytes, out _);
    Debug.Assert(success);

    await context.Response.WriteAsync($"[Response] connectionId={connectionFeature.ConnectionId}; tlsClientHello.length={bytesReturned}; tlsclienthello start={string.Join(' ', bytes.AsSpan(0, 30).ToArray())}");
    await next(context);
});