How to create a file requests using .Net core API

I am trying to create a "file request" using .Net core API.

From Box Developer documentation:

BoxFileRequestObject fileRequest = await client.FileRequestsManager.GetFileRequestByIdAsync("12345");

URL: https://developer.box.com/reference/get-file-requests-id/

We are unable to get the method "GetFileRequestByIdAsync"

using the below code, It has GetFilePreviewAsync. Please help us with this.

Code:

  var boxhelper = new BoxHelper(_configuration);

boxhelper.CreateClient(_configuration);

BoxFileRequest fileRequest = await boxhelper.client.FilesManager.GetFilePreviewAsync