public Node addNode(Coordinate coord){
  Node node=(Node)nodeMap.get(coord);
  if (node == null) {
    node=nodeFact.createNode(coord);
    nodeMap.put(coord,node);
  }
  return node;
}

public Node addNode ( Coordinate coord ) { Node node = ( Node ) nodeMap . get ( coord ) ; if ( node == null ) { node = nodeFact . createNode ( coord ) ; nodeMap . put ( coord , node ) ; } return node ; }
this method expects that a node has a coordinate value .
