ForceInstance 与 nonForceInstance

private List<Connection> cloneConnectionsForceInstance() {
  List<Connection> newList = new ArrayList<Connection>();
  if (connections != null)
      newList.addAll(connections);
  return newList;
}

private List<Connection> cloneConnections() {
  if (connections == null)
      return null;
  List<Connection> newList = new ArrayList<Connection>();
  newList.addAll(connections);
  return newList;
}