@Nullable
  private List<UsageInfo> getSelectedUsageInfos() {
    TreePath[] paths = myTree.getSelectionPaths();
    if (paths == null) return null;
    final ArrayList<UsageInfo> result = new ArrayList<>();
    for (TreePath path : paths) {
      SliceNode sliceNode = fromPath(path);
      if (sliceNode != null) {
        final SliceUsage sliceUsage = sliceNode.getValue();
        if (sliceUsage != null) {
          result.add(sliceUsage.getUsageInfo());
        }
      }
    }
    if (result.isEmpty()) return null;
    return result;
  }
@Nullable
  private List<UsageInfo> getSelectedUsageInfos()