*     #from(ValueGraph)}.
 * @since 20.0
 */
public final class ValueGraphBuilder<N, V> extends AbstractGraphBuilder<N> {

  /** Creates a new instance with the specified edge directionality. */
  private ValueGraphBuilder(boolean directed) {
    super(directed);
  }

  /** Returns a {@link ValueGraphBuilder} for building directed graphs. */
  public static ValueGraphBuilder<Object, Object> directed() {
    return new ValueGraphBuilder<>(true);

  }

  /**
   * Tests that the ImmutableValueGraph.Builder doesn't change when the creating ValueGraphBuilder
   * changes.
   */
  @Test
  @SuppressWarnings("CheckReturnValue")
  public void immutableValueGraphBuilder_copiesGraphBuilder() {
    ValueGraphBuilder<String, Object> graphBuilder =
        ValueGraphBuilder.directed()
            .allowsSelfLoops(true)
            .<String>nodeOrder(ElementOrder.<String>natural());

  }

  /**
   * Tests that the ImmutableValueGraph.Builder doesn't change when the creating ValueGraphBuilder
   * changes.
   */
  @Test
  @SuppressWarnings("CheckReturnValue")
  public void immutableValueGraphBuilder_copiesGraphBuilder() {
    ValueGraphBuilder<String, Object> graphBuilder =
        ValueGraphBuilder.directed()
            .allowsSelfLoops(true)
            .<String>nodeOrder(ElementOrder.<String>natural());

@SuppressWarnings("Immutable") // Extends StandardValueGraph but uses ImmutableMaps.
public final class ImmutableValueGraph<N, V> extends StandardValueGraph<N, V> {

  private ImmutableValueGraph(ValueGraph<N, V> graph) {
    super(ValueGraphBuilder.from(graph), getNodeConnections(graph), graph.edges().size());
  }

  /** Returns an immutable copy of {@code graph}. */
  public static <N, V> ImmutableValueGraph<N, V> copyOf(ValueGraph<N, V> graph) {

import org.jspecify.annotations.Nullable;

/**
 * Standard implementation of {@link MutableValueGraph} that supports both directed and undirected
 * graphs. Instances of this class should be constructed with {@link ValueGraphBuilder}.
 *
 * <p>Time complexities for mutation methods are all O(1) except for {@code removeNode(N node)},
 * which is in O(d_node) where d_node is the degree of {@code node}.
 *
 * @author James Sexton

  private static final AbstractGraphBuilder<?> graphBuilderA =
      GraphBuilder.directed().expectedNodeCount(10);
  private static final AbstractGraphBuilder<?> graphBuilderB =
      ValueGraphBuilder.directed().allowsSelfLoops(true).expectedNodeCount(16);

  private static final ImmutableGraph<String> IMMUTABLE_GRAPH_A =
      GraphBuilder.directed().<String>immutable().addNode("A").build();

  private static final AbstractGraphBuilder<?> graphBuilderA =
      GraphBuilder.directed().expectedNodeCount(10);
  private static final AbstractGraphBuilder<?> graphBuilderB =
      ValueGraphBuilder.directed().allowsSelfLoops(true).expectedNodeCount(16);

  private static final ImmutableGraph<String> IMMUTABLE_GRAPH_A =
      GraphBuilder.directed().<String>immutable().addNode("A").build();