public Object[] getChildren() {
    if (myChildren == null) {
      if (myFiles == null) {
        myFiles = getFileSystemRoots();
      }

      myChildren = myFiles.stream().
        filter(Objects::nonNull).
        map(file -> new FileElement(file, file.getPresentableUrl())).
        toArray();
    }
    return myChildren;
  }
public Object[] getChildren()