undirectedGraph.addNode(node3);
undirectedGraph.addNode(node4);
undirectedGraph.addNode(node5);
undirectedGraph.addNode(node6);
undirectedGraph.addNode(node7);
Edge edge12 = graphModel.factory().newEdge(node1, node2, false);
Edge edge13 = graphModel.factory().newEdge(node1, node3, false);
Edge edge14 = graphModel.factory().newEdge(node1, node4, false);
Edge edge15 = graphModel.factory().newEdge(node1, node5, false);
Edge edge16 = graphModel.factory().newEdge(node1, node6, false);
Edge edge27 = graphModel.factory().newEdge(node2, node7, false);