*
   * @throws IllegalArgumentException if {@code incidentEdgeOrder} is not either {@code
   *     ElementOrder.unordered()} or {@code ElementOrder.stable()}.
   * @since 29.0
   */
  public <N1 extends N> GraphBuilder<N1> incidentEdgeOrder(ElementOrder<N1> incidentEdgeOrder) {
    checkArgument(
        incidentEdgeOrder.type() == ElementOrder.Type.UNORDERED
            || incidentEdgeOrder.type() == ElementOrder.Type.STABLE,

   * @throws IllegalArgumentException if {@code incidentEdgeOrder} is not either {@code
   *     ElementOrder.unordered()} or {@code ElementOrder.stable()}.
   * @since 29.0
   */
  public <N1 extends N> ValueGraphBuilder<N1, V> incidentEdgeOrder(
      ElementOrder<N1> incidentEdgeOrder) {
    checkArgument(
        incidentEdgeOrder.type() == ElementOrder.Type.UNORDERED
            || incidentEdgeOrder.type() == ElementOrder.Type.STABLE,

 *
 * @author James Sexton
 */
abstract class AbstractGraphBuilder<N> {
  final boolean directed;
  boolean allowsSelfLoops = false;
  ElementOrder<N> nodeOrder = ElementOrder.insertion();
  ElementOrder<N> incidentEdgeOrder = ElementOrder.unordered();

  @Nullable Integer expectedNodeCount = null;

  /**
   * Creates a new instance with the specified edge directionality.
   *

    private final MutableGraph<N> mutableGraph;

    Builder(GraphBuilder<N> graphBuilder) {
      // The incidentEdgeOrder for immutable graphs is always stable. However, we don't want to
      // modify this builder, so we make a copy instead.
      this.mutableGraph = graphBuilder.copy().incidentEdgeOrder(ElementOrder.<N>stable()).build();
    }

    /**
     * Adds {@code node} if it is not already present.
     *

   *
   * <p>This instance is only useful in combination with {@code incidentEdgeOrder}, e.g. {@code
   * graphBuilder.incidentEdgeOrder(ElementOrder.stable())}.
   *
   * <h3>In combination with {@code incidentEdgeOrder}</h3>
   *
   * <p>{@code incidentEdgeOrder(ElementOrder.stable())} guarantees the ordering of the returned
   * collections of the following methods:
   *
   * <ul>

    Builder(ValueGraphBuilder<N, V> graphBuilder) {
      // The incidentEdgeOrder for immutable graphs is always stable. However, we don't want to
      // modify this builder, so we make a copy instead.
      this.mutableValueGraph =
          graphBuilder.copy().incidentEdgeOrder(ElementOrder.<N>stable()).build();
    }

    /**
     * Adds {@code node} if it is not already present.

    graph = ValueGraphBuilder.directed().incidentEdgeOrder(ElementOrder.unordered()).build();
    assertThat(graph.incidentEdgeOrder()).isEqualTo(ElementOrder.unordered());
  }

  @Test
  public void incidentEdgeOrder_stable() {
    graph = ValueGraphBuilder.directed().incidentEdgeOrder(ElementOrder.stable()).build();
    assertThat(graph.incidentEdgeOrder()).isEqualTo(ElementOrder.stable());
  }

  @Test

    graph = ValueGraphBuilder.directed().incidentEdgeOrder(ElementOrder.unordered()).build();
    assertThat(graph.incidentEdgeOrder()).isEqualTo(ElementOrder.unordered());
  }

  @Test
  public void incidentEdgeOrder_stable() {
    graph = ValueGraphBuilder.directed().incidentEdgeOrder(ElementOrder.stable()).build();
    assertThat(graph.incidentEdgeOrder()).isEqualTo(ElementOrder.stable());
  }

  @Test

   * {@link #edges()}, {@link #adjacentNodes(Object)}, {@link #predecessors(Object)}, {@link
   * #successors(Object)} and {@link #incidentEdges(Object)}.
   *
   * @since 29.0
   */
  ElementOrder<N> incidentEdgeOrder();

  /**
   * Returns a live view of this graph as a {@link Network} whose edges {@code E} are {@code
   * EndpointPair<N>} objects (that is, a {@code Network<N, EndpointPair<N>>}). The resulting {@code

      }

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

      @Override
      public ElementOrder<N> incidentEdgeOrder() {
        return AbstractValueGraph.this.incidentEdgeOrder();
      }

      @Override
      public Set<N> adjacentNodes(N node) {
        return AbstractValueGraph.this.adjacentNodes(node);
      }

      @Override