private void process(@NotNull final File file) {
    File f;
    File parent = file.getParentFile();
    for (f = file; parent != null; f = parent, parent = parent.getParentFile()) {
      Collection<File> files = myParentToChildrenMap.get(parent);
      if (files == null) {
        myParentToChildrenMap.put(parent, files = new HashSet<>());
      }
      files.add(f);
    }
    myRoots.add(f);
  }
private void process(@NotNull final File file)