document content is null?

Trying to save signed docs on our server.  Looping through the doc collection, Content is null with code bellow:

  //retrieve signed package from one span
            var pkg = oss.GetPackage(req.PackageId);

            foreach (var doc in pkg.Documents)
            {
                //assume docName was set up according to a good pattern
                var path = "documents/" + doc.Name + ".pdf";
                File.WriteAllBytes(path, doc.Content);
            }

Code below works, but seems like a waste to call OneSpan for each doc in the package.

 foreach (var doc in pkg.Documents)
            {
                //assume docName was set up according to a good pattern
                var path = "documents/" + doc.Name + ".pdf";
                byte[] pdfDocumentBytes = oss.Client.DownloadDocument(pkg.Id, doc.Id);
                File.WriteAllBytes(path, pdfDocumentBytes);
            }

Why does doc object have a Content prop if it is empty?