@Override
    public boolean equals(Object o) {
      if (this == o) return true;
      if (o == null || getClass() != o.getClass()) return false;
      NodeChange that = (NodeChange)o;
      return nodeChangeType == that.nodeChangeType &&
             Objects.equals(parentNode, that.parentNode) &&
             Objects.equals(childNode, that.childNode);
    }
@Override
    public boolean equals(Object o)