public bool TryGetFileExtension(string documentType, out string fileExtension)
{
if (string.IsNullOrEmpty(documentType)) throw new ArgumentNullException(nameof(documentType));
fileExtension = string.Empty;
if (_templateCollection.Count == 0) return false;
var templateBundle = _templateCollection[documentType];
// Get default template extension
if (templateBundle == null) return false;
fileExtension = templateBundle.Extension;
return true;
}