Edge edge27 = graphModel.factory().newEdge(node2, node7, false);
Edge edge37 = graphModel.factory().newEdge(node3, node7, false);
Edge edge47 = graphModel.factory().newEdge(node4, node7, false);
Edge edge57 = graphModel.factory().newEdge(node5, node7, false);
Edge edge67 = graphModel.factory().newEdge(node6, node7, false);
undirectedGraph.addEdge(edge12);
undirectedGraph.addEdge(edge13);
undirectedGraph.addEdge(edge14);
undirectedGraph.addEdge(edge15);
undirectedGraph.addEdge(edge16);
undirectedGraph.addEdge(edge27);