My project using Microsoft.Graph 5.15 version send an email with large attachment. I searched the web and find the below code. However there are some issues:

1.MessageItemRequestBuilder.Send cannot be use like a method

2.AttachmentsItemRequestBuilder.CreateUploadSession cannot be use like a method

There are my code snippet

   var savedDraft = await _graphClient.Users[userId].Messages.PostAsync(draftMessage);

    // Handle large attachments
   foreach (var largeAttachment in largeAttachments)
   {
      var fileStream = File.OpenRead(largeAttachment.FullName);
     var uploadSession = await _thisGraphClient.Users[userId]
         .Messages[savedDraft.Id]
         .Attachments
         .CreateUploadSession(new AttachmentItem
         {
             AttachmentType = AttachmentType.File,
             Name = largeAttachment.Name,
             Size = fileStream.Length,
             ContentType = "application/octet-stream"
         })
         .Request()
         .PostAsync();

     int maxSliceSize = 320 * 1024; // 320 KB - Change this to fit your needs
     var fileUploadTask = new LargeFileUploadTask<FileAttachment>(uploadSession, fileStream, maxSliceSize);

     var totalLength = fileStream.Length;
     IProgress<long> progress = new Progress<long>(prog =>
     {
         Console.WriteLine($"Uploaded {prog} bytes of {totalLength} bytes");
     });

     try
     {
         var uploadResult = await fileUploadTask.UploadAsync(progress);
         Console.WriteLine(uploadResult.UploadSucceeded ? "Upload complete" : "Upload failed");
     }
     catch (ServiceException ex)
     {
         Console.WriteLine($"Error uploading: {ex.ToString()}");
     }
 }

 // Send the draft
   await _thisGraphClient.Users[userId].Messages[savedDraft.Id].Send().Request().PostAsync();

Would someone tell me what should fix it. Thanks.