* equivalent to {@code nodes().contains(nodeU) && successors(nodeU).contains(nodeV)}, and to
   * {@code edgeConnectingOrNull(nodeU, nodeV) != null}.
   *
   * <p>In an undirected network, this is equal to {@code hasEdgeConnecting(nodeV, nodeU)}.
   *
   * @since 23.0
   */
  boolean hasEdgeConnecting(N nodeU, N nodeV);

  /**

        nodes.add(node);
    }

    /**
     * find a node by the GAV (metadata)
     *
     * @param md
     */
    public MetadataGraphNode findNode(MavenArtifactMetadata md) {
        for (MetadataGraphNode mgn : nodes) {
            if (mgn.metadata.equals(md)) {
                return mgn;
            }
        }

        MetadataGraphNode node = new MetadataGraphNode(md);
        addNode(node);

)

var (
	healthNodesOfflineCountMD = NewGaugeMD(healthNodesOfflineCount,
		"Count of offline nodes in the cluster")
	healthNodesOnlineCountMD = NewGaugeMD(healthNodesOnlineCount,
		"Count of online nodes in the cluster")
)

// loadClusterHealthNodeMetrics - `MetricsLoaderFn` for cluster health node
// metrics.
func loadClusterHealthNodeMetrics(ctx context.Context, m MetricValues,
	c *metricsCache,
) error {

    for (E key : keys) {
      LockGraphNode node = new LockGraphNode(getLockName(key));
      nodes.add(node);
      map.put(key, node);
    }
    // Pre-populate all allowedPriorLocks with nodes of smaller ordinal.
    for (int i = 1; i < numKeys; i++) {
      nodes.get(i).checkAcquiredLocks(Policies.THROW, nodes.subList(0, i));
    }
    // Pre-populate all disallowedPriorLocks with nodes of larger ordinal.

  @Test
  public void nodes_checkReturnedSetMutability() {
    assume().that(graphIsMutable()).isTrue();

    Set<Integer> nodes = network.nodes();
    assertThrows(UnsupportedOperationException.class, () -> nodes.add(N2));
    addNode(N1);
    assertThat(network.nodes()).containsExactlyElementsIn(nodes);
  }

  @Override
  @Test
  public void edges_checkReturnedSetMutability() {
    assume().that(graphIsMutable()).isTrue();

  @Test
  public void nodes_checkReturnedSetMutability() {
    assume().that(graphIsMutable()).isTrue();

    Set<Integer> nodes = network.nodes();
    assertThrows(UnsupportedOperationException.class, () -> nodes.add(N2));
    addNode(N1);
    assertThat(network.nodes()).containsExactlyElementsIn(nodes);
  }

  @Override
  @Test
  public void edges_checkReturnedSetMutability() {
    assume().that(graphIsMutable()).isTrue();

    for (Integer node : graph.nodes()) {
      new EqualsTester()
          .addEqualityGroup(
              graph.predecessors(node), graph.successors(node), graph.adjacentNodes(node))
          .testEquals();
    }
  }

  @Override
  @Test
  public void nodes_checkReturnedSetMutability() {
    assume().that(graphIsMutable()).isTrue();

    Set<Integer> nodes = graph.nodes();

import java.util.List;

/**
 * MetadataGraph node - as it's a directed graph - holds adjacency lists for incident and exident nodes
 *
 *
 */
@Deprecated
public class MetadataGraphNode {
    /** node payload */
    MavenArtifactMetadata metadata;

    /** nodes, incident to this (depend on me) */
    List<MetadataGraphNode> inNodes;

    /** nodes, exident to this (I depend on) */

  public void validateUndirectedEdges() {
    for (Integer node : network.nodes()) {
      new EqualsTester()
          .addEqualityGroup(
              network.inEdges(node), network.outEdges(node), network.incidentEdges(node))
          .testEquals();
      new EqualsTester()
          .addEqualityGroup(
              network.predecessors(node), network.successors(node), network.adjacentNodes(node))
          .testEquals();

    ASSERT_EQ(nodes.size(), fdef.node_def_size())
        << "Got unexpected number of nodes. Expected: ["
        << absl::StrJoin(nodes, ", ")
        << "] Actual nodes in fdef: " << fdef.DebugString();
    for (const NodeDef& node_def : fdef.node_def()) {
      ASSERT_TRUE(nodes.find(node_def.name()) != nodes.end())
          << "Got unexpected node: " << node_def.name()