@Nullable private static VcsFileRevision getRevisionAt(final TreeTableView treeTable, final int index) {
    final List items = treeTable.getItems();
    if (items.size() <= index) {
      return null;
    } else {
      return ((TreeNodeAdapter)items.get(index)).getRevision();
    }

  }
@Nullable private static VcsFileRevision getRevisionAt(final TreeTableView treeTable, final int index)