return copy;
  }

  /**
   * Not supported. Use {@link #eraseAll} instead.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Use {@link #eraseAll}
   */
  @DoNotCall("Always throws UnsupportedOperationException")
  @Override
  @Deprecated
  public void clear() {
    throw new UnsupportedOperationException();
  }

   * independent stream each time it is called.
   *
   * <p>The caller is responsible for ensuring that the returned stream is closed.
   *
   * @throws IOException if an I/O error occurs while opening the stream
   */
  public abstract OutputStream openStream() throws IOException;

  /**
   * Opens a new buffered {@link OutputStream} for writing to this sink. The returned stream is not

   * independent stream each time it is called.
   *
   * <p>The caller is responsible for ensuring that the returned stream is closed.
   *
   * @throws IOException if an I/O error occurs while opening the stream
   */
  public abstract OutputStream openStream() throws IOException;

  /**
   * Opens a new buffered {@link OutputStream} for writing to this sink. The returned stream is not

  }

  @GwtIncompatible // concurrency

  public void testConcurrentAdvance() throws Exception {
    FakeTicker ticker = new FakeTicker();

    int numberOfThreads = 64;
    runConcurrentTest(
        numberOfThreads,
        new Callable<@Nullable Void>() {
          @Override
          public @Nullable Void call() throws Exception {
            // adds two nanoseconds to the ticker
            ticker.advance(1L);

        throws InterruptedException {
      throw new UnsupportedOperationException();
    }

    @Override
    public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
        throws ExecutionException, InterruptedException {
      throw new UnsupportedOperationException();
    }

    @Override

   * {@code view} returned by this method will be invalidated, and will throw {@code
   * IllegalStateException} if it is accessed in any way, with the following exceptions:
   *
   * <ul>
   *   <li>{@code view.equals(view)} evaluates to {@code true} (but any other {@code equals(...)}
   *       expression involving {@code view} will throw)
   *   <li>{@code hashCode()} does not throw

     * @return The resolved plugin artifact, never {@code null}.
     * @throws PluginResolutionException If the plugin artifact could not be resolved.
     */
    Artifact resolve(Plugin plugin, List<RemoteRepository> repositories, RepositorySystemSession session)
            throws PluginResolutionException;

    /**
     * Resolves the runtime dependencies of the specified plugin.
     *

                throws ToolchainManagerException {
            return getDelegate().getToolchains(session, type, requirements);
        }

        @Nonnull
        @Override
        public Optional<org.apache.maven.api.Toolchain> getToolchainFromBuildContext(
                @Nonnull Session session, @Nonnull String type) throws ToolchainManagerException {

    public static ArtifactRepository buildArtifactRepository(org.apache.maven.settings.Repository repo)
            throws InvalidRepositoryException {
        return buildArtifactRepository(fromSettingsRepository(repo));
    }

    public static ArtifactRepository buildArtifactRepository(org.apache.maven.model.Repository repo)
            throws InvalidRepositoryException {
        if (repo != null) {
            String id = repo.getId();

     */
    protected Metadata readMetadata(File mappingFile) throws RepositoryMetadataReadException {

        try (InputStream in = Files.newInputStream(mappingFile.toPath())) {
            return new Metadata(new MetadataStaxReader().read(in, false));
        } catch (FileNotFoundException e) {
            throw new RepositoryMetadataReadException("Cannot read metadata from '" + mappingFile + "'", e);