* matches the insertion order. All optional operations (adding and removing) are supported. All
 * elements, including {@code null}, are permitted.
 *
 * <p>{@code contains(x)}, {@code add(x)} and {@code remove(x)}, are all (expected and amortized)
 * constant time operations. Expected in the hashtable sense (depends on the hash function doing a

        String value = transformer.getSingleNodeValue(document, "//BODY", node -> node);
        assertEquals("aaa", value);

        value = transformer.getSingleNodeValue(document, "//META[@name='keywords']/@content", node -> node);
        assertEquals("bbb", value);

        value = transformer.getSingleNodeValue(document, "//META[@name='keywords']/@content|//BODY", node -> node);
        assertEquals("bbb aaa", value);
    }

 */
package org.apache.maven.internal.impl;

import java.util.Collection;
import java.util.List;

import org.apache.maven.api.Artifact;
import org.apache.maven.api.DependencyCoordinate;
import org.apache.maven.api.Node;
import org.apache.maven.api.Project;
import org.apache.maven.api.RemoteRepository;
import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.di.Named;
import org.apache.maven.api.di.Singleton;

    }

    @Test
    void testCollectArtifactDependencies() {
        Artifact artifact =
                session.createArtifact("org.codehaus.plexus", "plexus-container-default", "1.0-alpha-32", "jar");
        Node root = session.collectDependencies(artifact);
        assertNotNull(root);
    }

    @Test
    void testResolveArtifactCoordinateDependencies() {

import org.apache.maven.api.Dependency;
import org.apache.maven.api.Node;
import org.apache.maven.api.RemoteRepository;
import org.apache.maven.api.annotations.Nonnull;
import org.eclipse.aether.graph.DependencyNode;

class WrapperNode extends AbstractNode {
    protected final Node delegate;
    protected final List<Node> children;

    WrapperNode(Node delegate, List<Node> children) {
        this.delegate = delegate;

        this();

        this.entry = entry;
    }

    public MetadataGraph() {
        nodes = new ArrayList<>(64);
    }

    public void addNode(MetadataGraphNode node) {
        nodes.add(node);
    }

    /**
     * find a node by the GAV (metadata)
     *
     * @param md
     */
    public MetadataGraphNode findNode(MavenArtifactMetadata md) {
        for (MetadataGraphNode mgn : nodes) {

     *
     * @return the exceptions that occurred, never {@code null}
     */
    @Nonnull
    List<Exception> getExceptions();

    /**
     * Gets the root node of the dependency graph.
     *
     * @return the root node of the dependency graph or {@code null} if none
     */
    @Nullable
    Node getRoot();

        return node;
    }

    @Override
    public Artifact getArtifact() {
        return node.getArtifact() != null ? session.getArtifact(node.getArtifact()) : null;
    }

    @Override
    public Dependency getDependency() {
        return node.getDependency() != null ? session.getDependency(node.getDependency()) : null;
    }

    @Override
    public List<Node> getChildren() {

        return node;
    }

    @Override
    public Artifact getArtifact() {
        return node.getArtifact() != null ? session.getArtifact(node.getArtifact()) : null;
    }

    @Override
    public Dependency getDependency() {
        return node.getDependency() != null ? session.getDependency(node.getDependency()) : null;
    }

    @Override
    public List<Node> getChildren() {

    private void processTreeNodes(MetadataGraphVertex parentVertex, MetadataTreeNode node, int depth, int pomOrder)
            throws MetadataResolutionException {
        if (node == null) {
            return;
        }

        MetadataGraphVertex vertex = new MetadataGraphVertex(node.md, versionedVertices, scopedVertices);
        if (!vertices.contains(vertex)) {
            vertices.add(vertex);