private void CreateImportNodeIfRequired(string library, string hashKey = null)
 {
     if (null == hashKey)
     {
         string libraryPath = string.Empty;
         if (GraphUtilities.TryGetImportLibraryPath(library, out libraryPath, out hashKey))
         {
             library = libraryPath;
         }
     }
     if (!importNodesMapping.ContainsKey(hashKey))
     {
         importNodesMapping.Add(hashKey, GraphUtilities.GenerateUID());
     }
     gc.CreateImportNode(importNodesMapping[hashKey], library);
 }