}

    @Override
    public @Nullable V edgeValueOrDefault(N nodeU, N nodeV, @Nullable V defaultValue) {
      return delegate().edgeValueOrDefault(nodeV, nodeU, defaultValue); // transpose
    }

    @Override
    public @Nullable V edgeValueOrDefault(EndpointPair<N> endpoints, @Nullable V defaultValue) {
      return delegate().edgeValueOrDefault(transpose(endpoints), defaultValue);
    }
  }

    }

    @Override
    public @Nullable V edgeValueOrDefault(N nodeU, N nodeV, @Nullable V defaultValue) {
      return delegate().edgeValueOrDefault(nodeV, nodeU, defaultValue); // transpose
    }

    @Override
    public @Nullable V edgeValueOrDefault(EndpointPair<N> endpoints, @Nullable V defaultValue) {
      return delegate().edgeValueOrDefault(transpose(endpoints), defaultValue);
    }
  }

    assertThat(transpose).isEqualTo(expectedTranspose);
    assertThat(transpose(transpose)).isSameInstanceAs(directedGraph);
    AbstractGraphTest.validateGraph(transpose.asGraph());

    assertThat(transpose.edgeValueOrDefault(N1, N2, null)).isNull();
    for (Integer node : directedGraph.nodes()) {
      assertThat(directedGraph.inDegree(node)).isSameInstanceAs(transpose.outDegree(node));