synchronized ( PROTOCOL_HANDLERS ) {
            URLStreamHandler handler = PROTOCOL_HANDLERS.get(protocol);
            if ( handler != null )
                return handler;
            if ( factory != null ) {
                handler = factory.createURLStreamHandler(protocol);
            }
            if ( handler == null ) {

            throws IOException {
        synchronized (PROTOCOL_HANDLERS) {
            URLStreamHandler handler = (URLStreamHandler)
                    PROTOCOL_HANDLERS.get(protocol);
            if (handler != null) return handler;
            if (factory != null) {
                handler = factory.createURLStreamHandler(protocol);
            }
            if (handler == null) {

 */
package org.apache.maven.artifact.handler.manager;

import java.util.Map;

import org.apache.maven.artifact.handler.ArtifactHandler;

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

    ArtifactHandler getArtifactHandler(String type);

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

    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

    }

    @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");
    }

   * 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();
   * }</pre>
   *

   *
   * <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())
   *         .build();
   * }</pre>
   *

                ArtifactHandler handler =
                        container.lookup(ArtifactHandlerManager.class).getArtifactHandler(type);
                assertEquals(handler.getExtension(), extension, type + " extension");
                // Packaging/Directory is Maven1 remnant!!!
                // assertEquals(handler.getPackaging(), packaging, type + " packaging");

        }
      };

  @Override
  protected final void tearDown() {
    tearDownStack.runTearDown();
    assertNull(
        "exceptions should not be propagated to uncaught exception handlers",
        thrownByExecutionThread);
  }

  public void testServiceStartStop() throws Exception {
    WaitOnRunService service = new WaitOnRunService();
    assertFalse(service.startUpCalled);

                    /*
                     * Most existing extensions don't define exported packages, i.e. no classes are to be exposed to
                     * plugins, yet the components provided by the extension (e.g. artifact handlers) must be
                     * accessible, i.e. we still must import the extension realm into the project realm.
                     */
                    exports = Arrays.asList(extensionRealm.getId());
                }