undirectedGraph.addNode(node3);
undirectedGraph.addNode(node4);
undirectedGraph.addNode(node5);
undirectedGraph.addNode(node6);
undirectedGraph.addNode(node7);
undirectedGraph.addNode(node8);
Edge edge12 = graphModel.factory().newEdge(node1, node2, false);
Edge edge13 = graphModel.factory().newEdge(node1, node3, false);
Edge edge34 = graphModel.factory().newEdge(node3, node4, false);
Edge edge24 = graphModel.factory().newEdge(node2, node4, false);
Edge edge56 = graphModel.factory().newEdge(node5, node6, false);