Does not handle native nested arrays (payload is empty / deleted)

[wire67]

      $val = [
         'timestamp' => new FirestoreTimestamp,
         'a' => ['b'=>['c'=>'test']],
      ];
      $ret = $firestoreClient->updateDocument($path, $val);

Unable to handle nested native arrays.
This code will fail, and add no fields to the document, if the given fields are present they will be deleted, there is no exception raised, payload will just be empty.