Graph graph3 = new Graph();
        graph3.addVertex("a");
        graph3.addVertex("b");
        graph3.addVertex("c");
        graph3.addVertex("d");
        graph3.addVertex("e");
        graph3.addVertex("f");
        addEdge(graph3, "a", "b");
        addEdge(graph3, "b", "c");
        addEdge(graph3, "b", "d");
        addEdge(graph3, "c", "d");
        addEdge(graph3, "c", "e");
        addEdge(graph3, "f", "d");

import java.util.List;
import java.util.Map;
import java.util.Set;

class Graph {

    final Map<String, Set<String>> graph = new LinkedHashMap<>();

    synchronized void addEdge(String from, String to) throws CycleDetectedException {
        if (graph.computeIfAbsent(from, l -> new HashSet<>()).add(to)) {
            List<String> cycle = visitCycle(graph, Collections.singleton(to), new HashMap<>(), new LinkedList<>());

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.project;

import java.util.*;

class Graph {
    private enum DfsState {
        VISITING,
        VISITED
    }

    final Map<String, Vertex> vertices = new LinkedHashMap<>();

    public Vertex getVertex(String id) {
        return vertices.get(id);

         *       v3-v4
         *
         */
        v1 = graph.addVertex(new ArtifactMetadata("g", "a1", "1.0"));
        graph.setEntry(v1);
        v2 = graph.addVertex(new ArtifactMetadata("g", "a2", "1.0"));
        v3 = graph.addVertex(new ArtifactMetadata("g", "a3", "1.0"));
        v4 = graph.addVertex(new ArtifactMetadata("g", "a4", "1.0"));

        // v1-->v2
        graph.addEdge(v1, v2, new MetadataGraphEdge("1.1", true, null, null, 2, 1));

     * in <code>ArtifactScopeEnum</code>
     *
     * @param graph the "dirty" graph to be simplified via conflict resolution
     * @param scope scope for which the graph should be resolved
     *
     * @return resulting "clean" graph for the specified scope
     *
     * @since 3.0
     */
    MetadataGraph resolveConflicts(MetadataGraph graph, ArtifactScopeEnum scope)
            throws GraphConflictResolutionException;

    private final Map<MavenProject, Integer> order;

    private final Map<String, MavenProject> projects;

    /**
     * Creates a new project dependency graph based on the specified projects.
     *
     * @param projects The projects to create the dependency graph with
     * @throws DuplicateProjectException
     * @throws CycleDetectedException
     */
    public DefaultProjectDependencyGraph(Collection<MavenProject> projects)

    Node getNode(org.eclipse.aether.graph.DependencyNode node);

    Node getNode(org.eclipse.aether.graph.DependencyNode node, boolean verbose);

    @Nonnull
    Artifact getArtifact(@Nonnull org.eclipse.aether.artifact.Artifact artifact);

    @Nonnull
    Dependency getDependency(@Nonnull org.eclipse.aether.graph.Dependency dependency);

 * for a given artifact and builds a graph of them.
 * The dependencies collection mechanism will not download any artifacts,
 * and only the pom files will be downloaded.
 *
 * @since 4.0.0
 */
@Experimental
public interface DependencyCollector extends Service {

    /**
     * Collects the transitive dependencies and builds a dependency graph.

         * Construct a new value source, using the supplied object as the root from
         * which to start, and using expressions split at the dot ('.') to navigate
         * the object graph beneath this root.
         * @param root the root of the graph.
         */
        public ObjectBasedValueSource(Object root) {
            super(true);
            this.root = root;
        }

        /**

import org.eclipse.aether.collection.CollectRequest;
import org.eclipse.aether.collection.CollectResult;
import org.eclipse.aether.collection.DependencyCollectionException;
import org.eclipse.aether.util.graph.manager.DependencyManagerUtils;
import org.eclipse.aether.util.graph.transformer.ConflictResolver;

import static org.apache.maven.internal.impl.Utils.nonNull;

@Named
@Singleton
public class DefaultDependencyCollector implements DependencyCollector {