private final Executor executor;

    public DefaultArtifactResolver() {
        int threads = Integer.getInteger("maven.artifact.threads", 5);
        if (threads <= 1) {
            executor = Runnable::run;
        } else {
            executor = new ThreadPoolExecutor(
                    threads, threads, 3, TimeUnit.SECONDS, new LinkedBlockingQueue<>(), new DaemonThreadCreator());
        }
    }

/**
 * Simple {@link ThreadFactory} implementation that ensures the corresponding threads have a meaningful name.
 */
public class BuildThreadFactory implements ThreadFactory {
    private final AtomicInteger id = new AtomicInteger();

    private static final String PREFIX = "BuilderThread";

    @Override
    public Thread newThread(Runnable r) {
        return new Thread(r, String.format("%s-%d", PREFIX, id.getAndIncrement()));
    }

 * <p>
 * This builder uses a number of threads equal to the minimum of the degree of concurrency (which is the thread count
 * set with <code>-T</code> on the command-line) and the number of projects to build. As such, building a single project
 * will always result in a sequential build, regardless of the thread count.
 * </p>

    // ----------------------------------------------------------------------------
    // We need to allow per execution user and global settings as the embedder
    // might be running in a mode where it's executing many threads with totally
    // different settings.
    // ----------------------------------------------------------------------------

    private File userSettingsFile;

    private File projectSettingsFile;

                                + "plugin(s) that have goals not marked as thread-safe to support parallel execution.",
                        "While this /may/ work fine, please look for plugin updates and/or "
                                + "request plugins be made thread-safe.",
                        "If reporting an issue, report it against the plugin in question, not against Apache Maven.")) {

        }
    }

    static class OwnerReentrantLock extends ReentrantLock {
        @Override
        public Thread getOwner() {
            return super.getOwner();
        }
    }

    static class OwnerReentrantReadWriteLock extends ReentrantReadWriteLock {
        @Override
        public Thread getOwner() {
            return super.getOwner();
        }
    }

    private static void warn(String msg) {

    private List<File> filesToDelete = new ArrayList<>();

    private final String baseFilename;

    private final String fileSuffix;

    private StackTraceElement callerInfo;

    private Thread cleanupWarning;

    private boolean warnAboutCleanup = false;

    public TestFileManager(String baseFilename, String fileSuffix) {
        this.baseFilename = baseFilename;
        this.fileSuffix = fileSuffix;

     * true}. If {@code false}, unknown elements will be ignored instead of causing a failure.
     */
    String IS_STRICT = "org.apache.maven.artifact.repository.metadata.io.isStrict";

    /**
     * Reads the metadata from the specified file.
     *
     * @param input The file to deserialize the metadata from, must not be {@code null}.

 * under the License.
 */
package org.apache.maven.api.services.xml;

import org.apache.maven.api.annotations.Experimental;
import org.apache.maven.api.plugin.descriptor.PluginDescriptor;

/**
 * Reads and writes a {@link PluginDescriptor} object to/from XML.
 *
 * @since 4.0.0
 */
@Experimental

        // lookups that occur in contextualize calls in line with the right realm.
        ClassRealm oldLookupRealm = container.setLookupRealm(pluginRealm);

        ClassLoader oldClassLoader = Thread.currentThread().getContextClassLoader();
        Thread.currentThread().setContextClassLoader(pluginRealm);

        try {
            if (mojoDescriptor.isV4Api()) {