public async Task <IActionResult> OnPostAsync(List <IFormFile> files)
        {
            if (files.Count == 1 && files[0].Length > 0)
            {
                var file = files[0];

                var avatar = new ConferenceDTO.File
                {
                    FileName    = Path.GetFileName(file.FileName),
                    ContentType = "image/png" //file.ContentType
                };

                MemoryStream memoryStream;
                using (var inputStream = file.OpenReadStream())
                {
                    _imageProcessor.GenerateAvatar(inputStream,
                                                   new SixLabors.Primitives.Size(200, 200),
                                                   100,
                                                   out memoryStream);

                    avatar.Content = memoryStream.ToArray();
                    memoryStream.Dispose();
                }

                Attendee.Avatar = avatar;
            }

            await _apiClient.AddAttendeeAsync(Attendee);

            return(RedirectToPage("/Index"));
        }