@Override
  @SuppressWarnings("SuspiciousMethodCalls")
  public int getIndexOfChild(Object object, Object child) {
    List<? extends T> list = getChildren(object);
    return list == null ? -1 : list.indexOf(child);
  }
@Override
  @SuppressWarnings("SuspiciousMethodCalls")
  public int getIndexOfChild(Object object, Object child)