implements ExtensibleEnumRegistry<T> {

        private final Map<String, T> values;

        DefaultExtensibleEnumRegistry(List<P> providers, T... builtinValues) {
            values = Stream.<T>concat(
                            Stream.of(builtinValues), providers.stream().flatMap(p -> p.provides().stream()))
                    .collect(Collectors.toMap(t -> t.id(), t -> t));
        }

        @Override

     * Retrieve a stream of the project's artifacts
     */
    private Stream<Artifact> getProjectArtifacts(MavenProject project) {
        Stream<org.apache.maven.artifact.Artifact> artifacts = Stream.concat(
                Stream.concat(
                        // pom artifact
                        Stream.of(new ProjectArtifact(project)),
                        // main project artifact if not a pom

     *
     * @return a stream containing this node and its descendant
     */
    @Nonnull
    default Stream<Node> stream() {
        return Stream.concat(Stream.of(this), getChildren().stream().flatMap(Node::stream));
    }

                boolean recursive) {
            List<Callable<InterimResult>> tasks = pomFiles.stream()
                    .map(pomFile -> ((Callable<InterimResult>)
                            () -> build(projectIndex, pomFile, concat(aggregatorFiles, pomFile), root, recursive)))
                    .collect(Collectors.toList());
            try {
                List<Future<InterimResult>> futures = executor.invokeAll(tasks);

            implements ExtensibleEnumRegistry<T> {

        protected final Map<String, T> values;

        DefaultExtensibleEnumRegistry(List<P> providers, T... builtinValues) {
            values = Stream.<T>concat(
                            Stream.of(builtinValues), providers.stream().flatMap(p -> p.provides().stream()))
                    .collect(Collectors.toUnmodifiableMap(t -> t.id().toLowerCase(Locale.ROOT), t -> t));
        }

        }
        return getModelId() + " " + getLocation();
    }

    public static InputSource merge(InputSource src1, InputSource src2) {
        return new InputSource(Stream.concat(src1.sources(), src2.sources()).collect(Collectors.toSet()));
    }

     * Do not include the POM artifact as the file can't be set anyway.
     */
    private Stream<org.apache.maven.artifact.Artifact> getProjectArtifacts(MavenProject project) {
        return Stream.concat(Stream.of(project.getArtifact()), project.getAttachedArtifacts().stream());
    }

    private String id(org.apache.maven.artifact.Artifact artifact) {
        return artifact.getGroupId()

    }

    @Inject
    public DefaultLifecycleRegistry(
            List<LifecycleProvider> providers, Map<String, org.apache.maven.lifecycle.Lifecycle> lifecycles) {
        super(
                concat(providers, new LifecycleWrapperProvider(lifecycles)),
                new CleanLifecycle(),
                new DefaultLifecycle(),
                new SiteLifecycle(),
                new WrapperLifecycle());

            }
        }

        /*
         * NOTE: This is primarily to keep backward-compat with Maven 2.x which did not validate that dependencies are
         * unique within a single POM. Upon multiple declarations, 2.x just kept the last one but retained the order of
         * the first occurrence. So when we're in lenient/compat mode, we have to deal with such broken POMs and mimic

                .collect(Collectors.toList());
    }

    private Map<String, Lifecycle> lookupLifecycles() {
        // TODO: Remove the following code when maven-compat is gone
        // This code is here to ensure maven-compat's EmptyLifecycleExecutor keeps on working.
        if (lookup == null) {
            return customLifecycles != null ? customLifecycles : new HashMap<>();
        }