*
     * @param request The execution request to populate, must not be {@code null}.
     * @param toolchains The toolchains to copy into the execution request, may be {@code null}.
     * @return The populated execution request, never {@code null}.
     * @throws MavenExecutionRequestPopulationException If the execution request could not be populated.
     * @since 3.3.0
     */

     *
     * @return The group id of the unresolvable model, can be empty but never {@code null}.
     */
    public String getGroupId() {
        return groupId;
    }

    /**
     * Gets the artifact id of the unresolvable model.
     *
     * @return The artifact id of the unresolvable model, can be empty but never {@code null}.
     */
    public String getArtifactId() {
        return artifactId;

    /**
     * Gets the identifier of this repository.
     *
     * @return the (case-sensitive) identifier, never {@code null}
     */
    @Nonnull
    String getId();

    /**
     * Gets the type of the repository, for example "default".
     *
     * @return the (case-sensitive) type of the repository, never {@code null}
     */
    @Nonnull
    String getType();

@Experimental
public interface Event {

    /**
     * Gets the type of the event.
     *
     * @return the type of the event, never {@code null}
     */
    @Nonnull
    EventType getType();

    /**
     * Gets the session from which this event originates.
     *
     * @return the current session, never {@code null}
     */
    @Nonnull
    Session getSession();

    /**
     * Gets the current project (if any).

     * is thrown so this information is merely meant to assist the user.
     *
     * @return The identifier of the project or an empty string if not known, never {@code null}.
     */
    String getProjectId();

    /**
     * Gets the POM file from which the project was built.
     *
     * @return The POM file or {@code null} if unknown.
     */
    File getPomFile();

     * @param session The repository session, must not be {@code null}.
     * @param artifactCoordinate The artifact coordinate for which the version needs to be resolved, must not be {@code null}
     * @return The version result, never {@code null}.
     * @throws VersionResolverException If the metaversion could not be resolved.
     */
    @Nonnull

     *            null}.
     * @param session The repository session to use for resolving the plugin's main artifact, must not be {@code null}.
     * @return The resolved plugin artifact, never {@code null}.
     * @throws PluginResolutionException If the plugin artifact could not be resolved.
     */
    Artifact resolve(Plugin plugin, List<RemoteRepository> repositories, RepositorySystemSession session)

     * configured directly by the user on his discretion, e.g. via the {@code -Dkey=value} parameter on the command
     * line.
     *
     * @return The user properties, never {@code null}.
     */
    public Properties getUserProperties() {
        return request.getUserProperties();
    }

    /**

 */
@Experimental
public interface DependencyCollectorResult {
    /**
     * Gets the exceptions that occurred while building the dependency graph.
     *
     * @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

    /**
     * Creates a human-friendly string representation of the specified object.
     *
     * @param obj The object to create a string representation for, may be <code>null</code>.
     * @return The string representation, never <code>null</code>.
     */
    private String toString(Object obj) {
        String str;
        if (obj != null && obj.getClass().isArray()) {
            int n = Array.getLength(obj);