* @since 4.0.0
 */
public interface ExtensibleEnumRegistry<T extends ExtensibleEnum> extends Service {
    @Nonnull
    Optional<T> lookup(@Nonnull String id);

    @Nonnull
    default T require(@Nonnull String id) {
        return lookup(id).orElseThrow(() -> new IllegalArgumentException("Unknown extensible enum value '" + id + "'"));
    }

     */
    @Nonnull
    Optional<Source> getInstallationToolchainsSource();

    /**
     * Gets the user Toolchains source.
     *
     * @return the user Toolchains source or {@code null} if none
     */
    @Nonnull
    Optional<Source> getUserToolchainsSource();

    @Nonnull
    static ToolchainsBuilderRequest build(
            @Nonnull ProtoSession session,

     * @return an identification of the patch-module path for the given module.
     *
     * @see Modular#moduleName()
     */
    @Nonnull
    public static Modular patchModule(@Nonnull String moduleName) {
        return PATCH_MODULE.new Modular(moduleName);
    }

    /**

import org.apache.maven.api.annotations.Nonnull;

/**
 *
 * @since 4.0.0
 */
@Experimental
public interface ArtifactManager extends Service {

    /**
     * Returns the path of the file previously associated to this artifact
     * or {@code Optional.empty()} if no path has been associated.
     */
    @Nonnull
    Optional<Path> getPath(@Nonnull Artifact artifact);

    /**

     * (prefixed with {@code env.}).
     *
     * @return the system properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getSystemProperties();

    /**
     * Returns the properly overlaid map of properties: system + user.
     */
    @Nonnull
    Map<String, String> getEffectiveProperties();

    /**
     * Returns the start time of the session.
     *

    /**
     * The packaging id.
     */
    @Nonnull
    @Override
    String id();

    /**
     * The language of this packaging.
     */
    @Nonnull
    default Language language() {
        return type().getLanguage();
    }

    /**
     * The type of main artifact produced by this packaging.
     */
    @Nonnull
    Type type();

    /**

     * @return the phase
     */
    @Nonnull
    String phase() default "";

    /**
     * Goal to fork. Note that specifying a phase overrides specifying a goal. The specified <code>goal</code> must be
     * another goal of the same plugin.
     * @return the goal
     */
    @Nonnull
    String goal() default "";

    /**

     *
     * @throws TransportProviderException if passed in remote repository has invalid remote URL or unsupported protocol.
     */
    @Nonnull
    Transport transport(@Nonnull Session session, @Nonnull RemoteRepository repository);

     *
     * @return the child nodes of this node, never {@code null}
     */
    @Nonnull
    List<Node> getChildren();

    /**
     * @return repositories of this node
     */
    @Nonnull
    List<RemoteRepository> getRemoteRepositories();

    /**
     * The repository where this artifact has been downloaded from.
     */
    @Nonnull
    Optional<RemoteRepository> getRepository();

    /**

                    Arrays.spliterator(new String[] {"abc", "", "de", "f", "g", ""}),
                    (String str) -> charactersOf(str).spliterator(),
                    Spliterator.SIZED | Spliterator.DISTINCT | Spliterator.NONNULL,
                    7))
        .expect('a', 'b', 'c', 'd', 'e', 'f', 'g');
  }

  public void testFlatMap_nullStream() {
    SpliteratorTester.of(
            () ->
                CollectSpliterators.flatMap(