* allows specification of the factory used in creating underlying
     * stream handlers. This can be called once per JVM instance.
     *
     * @param factory
     *            The URL stream handler factory.
     */
    public static void setURLStreamHandlerFactory ( URLStreamHandlerFactory factory ) {
        synchronized ( PROTOCOL_HANDLERS ) {
            if ( Handler.factory != null ) {

    return new Builder<>();
  }

  /**
   * A builder for creating immutable class-to-instance maps. Example:
   *
   * <pre>{@code
   * static final ImmutableClassToInstanceMap<Handler> HANDLERS =
   *     new ImmutableClassToInstanceMap.Builder<Handler>()
   *         .put(FooHandler.class, new FooHandler())
   *         .put(BarHandler.class, new SubBarHandler())
   *         .put(Handler.class, new QuuxHandler())

    private boolean includesDependencies;

    private String language;

    @Deprecated
    private boolean addedToClasspath;

    /**
     * Default ctor for Plexus compatibility, as many plugins have artifact handlers declared in legacy Plexus XML.
     * Do not use directly!
     *
     * @deprecated This ctor is present only for Plexus XML defined component compatibility, do not use it.
     */
    @Deprecated

     * allows specification of the factory used in creating underlying
     * stream handlers.  This can be called once per JVM instance.
     *
     * @param factory The URL stream handler factory.
     */
    public static void setURLStreamHandlerFactory(
            URLStreamHandlerFactory factory) {
        synchronized (PROTOCOL_HANDLERS) {
            if (Handler.factory != null) {
                throw new IllegalStateException(

public interface ArtifactHandlerManager {
    String ROLE = ArtifactHandlerManager.class.getName();

    ArtifactHandler getArtifactHandler(String type);

    @Deprecated
    void addHandlers(Map<String, ArtifactHandler> handlers);

    return new Builder<>();
  }

  /**
   * A builder for creating immutable type-to-instance maps. Example:
   *
   * <pre>{@code
   * static final ImmutableTypeToInstanceMap<Handler<?>> HANDLERS =
   *     ImmutableTypeToInstanceMap.<Handler<?>>builder()
   *         .put(new TypeToken<Handler<Foo>>() {}, new FooHandler())
   *         .put(new TypeToken<Handler<Bar>>() {}, new SubBarHandler())
   *         .build();

 * Provides the positional index of the project
 * </p>
 * <strong>NOTE:</strong> This class is not part of any public api and can be changed or deleted without prior notice.
 *
 * @since 3.0
 */
// TODO Kristian wonders if this class really is necessary and if it overlaps other concepts.
public final class ProjectIndex {

    private final Map<String, MavenProject> projects;

    private final Map<String, Integer> indices;

    }

    @Override
    public void addHandlers(Map<String, ArtifactHandler> handlers) {
        throw new UnsupportedOperationException("Adding handlers programmatically is not supported anymore");
    }

    @Deprecated
    public Set<String> getHandlerTypes() {
        throw new UnsupportedOperationException("Querying handlers programmatically is not supported anymore");
    }

@PlexusTest
class ArtifactHandlerTest {
    @Inject
    PlexusContainer container;

    @Test
    void testAptConsistency() throws Exception {
        File apt = getTestFile("src/site/apt/artifact-handlers.apt");

        List<String> lines = Files.readAllLines(apt.toPath());

        for (String line : lines) {
            if (line.startsWith("||")) {
                String[] cols = line.split("\\|\\|");

    return new Builder<>();
  }

  /**
   * A builder for creating immutable class-to-instance maps. Example:
   *
   * <pre>{@code
   * static final ImmutableClassToInstanceMap<Handler> HANDLERS =
   *     new ImmutableClassToInstanceMap.Builder<Handler>()
   *         .put(FooHandler.class, new FooHandler())
   *         .put(BarHandler.class, new SubBarHandler())
   *         .put(Handler.class, new QuuxHandler())