/guava/guava/src/com/google/common/graph/StandardNetwork.java
N nodeU = checkedConnections( edge) ;
N nodeU = checkedReferenceNode ( edge ) ;
@Override public Set<E> incidentEdges(N node) { return nodeInvalidatableSet(checkedConnections(node).incidentEdges(), node); } @Override public EndpointPair<N> incidentNodes(E edge) { <extra_id_0> N nodeV = requireNonNull(nodeConnections.get(nodeU)).adjacentNode(edge); return EndpointPair.of(this, nodeU, nodeV); } @Override public Set<N> adjacentNodes(N node) { return nodeInvalidatableSet(checkedConnections(node).adjacentNodes(), node);