@Override
      public ElementOrder<N> nodeOrder() {
        return AbstractNetwork.this.nodeOrder();
      }

      @Override
      public ElementOrder<N> incidentEdgeOrder() {
        // TODO(b/142723300): Return AbstractNetwork.this.incidentEdgeOrder() once Network has that
        //   method.
        return ElementOrder.unordered();
      }

      @Override
      public boolean isDirected() {