Node node5 = graphModel.factory().newNode("4");
directedGraph.addNode(node1);
directedGraph.addNode(node2);
directedGraph.addNode(node3);
directedGraph.addNode(node4);
directedGraph.addNode(node5);
Edge edge12 = graphModel.factory().newEdge(node1, node2);
Edge edge14 = graphModel.factory().newEdge(node1, node4);
Edge edge23 = graphModel.factory().newEdge(node2, node3);
Edge edge25 = graphModel.factory().newEdge(node2, node5);
Edge edge35 = graphModel.factory().newEdge(node3, node5);