/** creates a new dummy edge to be used in the graph */
@SuppressWarnings("unchecked")
private Edge newDummyEdge(Node targetNode, Node sourceNode) {
DummyEdgePart edgePart = new DummyEdgePart();
Edge edge = new Edge(edgePart, sourceNode, targetNode);
edge.weight = 1;
this.edgeList.add(edge);
return edge;
}