return EndpointPair.ordered(endpoints.target(), endpoints.source());
    }
    return endpoints;
  }

  // NOTE: this should work as long as the delegate graph's implementation of edges() (like that of
  // AbstractGraph) derives its behavior from calling successors().
  private static final class TransposedGraph<N> extends ForwardingGraph<N> {
    private final Graph<N> graph;

    TransposedGraph(Graph<N> graph) {

      return EndpointPair.ordered(endpoints.target(), endpoints.source());
    }
    return endpoints;
  }

  // NOTE: this should work as long as the delegate graph's implementation of edges() (like that of
  // AbstractGraph) derives its behavior from calling successors().
  private static final class TransposedGraph<N> extends ForwardingGraph<N> {
    private final Graph<N> graph;

    TransposedGraph(Graph<N> graph) {