public IEnumerable <string> GetBookmarkNames(int id)
{
var undFormVersion = _context.UndFormVersion.Find(id);
var getFilePath = undFormVersion.FileName.ToString();
//string newFileName = "EndrosementBlankPreview.pdf";
Document endorsement = new Document(getFilePath);
DocumentBuilder builder = new DocumentBuilder(endorsement);
BookmarkCollection bookmarks = endorsement.Range.Bookmarks;
var bookmarkNames = bookmarks.Select(b => b.Name);
return(bookmarkNames);
}