Node n2 = graphModel.factory().newNode("n2");
graph.addNode(n2);
Node n3 = graphModel.factory().newNode("n3");
graph.addNode(n3);
Node n4 = graphModel.factory().newNode("n4");
graph.addNode(n4, n3);
Edge e1 = graphModel.factory().newEdge(n1, n2, 1f, true);
graph.addEdge(e1);
Edge e2 = graphModel.factory().newEdge(n2, n4, 3f, true);
graph.addEdge(e2);