*
 * @since 4.0.0
 */
@Experimental
public interface TypeRegistry extends ExtensibleEnumRegistry<Type> {

    /**
     * Obtain the {@link Type} from the specified {@code id}.
     * If no type is known for {@code id}, the registry will
     * create a custom {@code Type} for it.
     *
     * @param id the id of the type to retrieve
     * @return the type
     */
    @Nonnull
    @Override

 * will be used to find POMs for children modules.
 *
 * @since 4.0.0
 */
public interface ModelSource extends Source {

    interface ModelLocator {
        /**
         * Returns the file containing the pom or null if a pom can not be
         * found at the given file or in the given directory.
         *
         * @since 4.0.0
         */
        @Nullable
        Path locateExistingPom(@Nonnull Path project);
    }

     * @param result The artifact descriptor result, never {@code null}.
     * @param model The artifact model, never {@code null}.
     * @return The {@link Artifact} to relocate to, or {@code null} if no relocation wanted.
     */
    Artifact relocatedTarget(RepositorySystemSession session, ArtifactDescriptorResult result, Model model)
            throws ArtifactDescriptorException;

    @Override
    public void extend(MavenExecutionRequest mavenExecutionRequest) {
        Map<String, PropertyContributor> effectivePropertyContributors = lookup.lookupMap(PropertyContributor.class);
        if (!effectivePropertyContributors.isEmpty()) {
            HashMap<String, String> userPropertiesMap = new HashMap<>((Map) mavenExecutionRequest.getUserProperties());

            ModelBuilderRequest request,
            ModelProblemCollector problems) {
        if (sources != null && !sources.isEmpty()) {
            Map<String, Dependency> dependencies = new LinkedHashMap<>();

            DependencyManagement depMgmt = target.getDependencyManagement();

            if (depMgmt != null) {
                for (Dependency dependency : depMgmt.getDependencies()) {

     * @return absolute path or {@code null} if the input was {@code null}
     */
    public String interpolate(String path, ProfileActivationContext context) throws InterpolationException {
        if (path == null) {
            return null;
        }

        RegexBasedInterpolator interpolator = new RegexBasedInterpolator();

        Path basedir = context.getProjectDirectory();

        if (basedir != null) {

        }

        public static Model deref(Holder holder) {
            return holder != null ? holder.get() : null;
        }

        public Model get() {
            if (!set) {
                synchronized (this) {
                    if (!set) {
                        try {
                            this.wait();
                        } catch (InterruptedException e) {
                            // Ignore

        Reader reader = request.getReader();
        InputStream inputStream = request.getInputStream();
        if (reader == null && inputStream == null) {
            throw new IllegalArgumentException("reader or inputStream must be non null");
        }
        try {
            InputSource source = null;
            if (request.getModelId() != null || request.getLocation() != null) {

    }

    @Override
    public boolean requiresProject(MavenSession session) {
        List<String> goals = session.getGoals();
        if (goals != null) {
            for (String goal : goals) {
                if (!isGoalSpecification(goal)) {
                    return true;
                }
            }
        }
        return false;
    }

            PluginInfo pluginInfo = extractPluginInfo(artifact);
            if (pluginInfo != null) {
                String key = pluginInfo.groupId;
                if (processedPlugins.get(key) == null) {
                    PluginsMetadata pluginMetadata = plugins.get(key);
                    if (pluginMetadata == null) {
                        pluginMetadata = new PluginsMetadata(pluginInfo, timestamp);