public DocumentRegistrationResponse DocumentRegistration(DocumentRegistrationRequest request, string filePath)
        {
            if (request == null)
                throw new ArgumentNullException("request");

            if (filePath == null)
                throw new ArgumentNullException("filePath");

            return DocumentRegistration(request, File.OpenRead(filePath), Path.GetFileName(filePath));
        }
        public DocumentRegistrationResponse DocumentRegistration(DocumentRegistrationRequest request, Stream fileStream, string fileName)
        {
            if (request == null)
                throw new ArgumentNullException("request");

            if (fileStream == null)
                throw new ArgumentNullException("fileStream");

            return UploadFile<DocumentRegistrationRequest, DocumentRegistrationResponse>(request, fileStream, fileName, "DocumentRegistration");
        }