this.attrs = attrs;
        this.options = options;
        this.tree = tree.acquire();
        this.tree_num = tree.getTreeId();

        if (cfg.isTraceResourceUsage()) {
            this.creationBacktrace = Thread.currentThread().getStackTrace();
        } else {
            this.creationBacktrace = null;
        }
    }

    /**
     * @param cfg
     * @param fid
     * @param tree
     * @param unc

 * invoke methods, they invoke methods on the {@code ForwardingMultiset}.
 *
 * <p>The {@code standard} methods and any collection views they return are not guaranteed to be
 * thread-safe, even when all of the methods that they depend on are thread-safe.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible

   * proceed to read the response body with [Response.body]. The response is still live until its
   * response body is [closed][ResponseBody]. The recipient of the callback may consume the response
   * body on another thread.
   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not
   * necessarily indicate application-layer success: `response` may still indicate an unhappy HTTP

/**
 * A record representing the result of a single request operation, containing the original request,
 * the result (if successful), and any error that occurred during processing.
 * <p>
 * This class is immutable and thread-safe, suitable for use in concurrent operations.
 *
 * @param <REQ> The type of the request
 * @param <REP> The type of the response, which must extend {@code Result<REQ>}
 * @param request The original request that was processed

    <include path="crawler/opensearch.xml"/>

	<!-- Crawler -->
	<component name="crawler" class="org.codelibs.fess.crawler.Crawler" instance="prototype" >
	</component>

	<!-- Crawler Thread -->
	<component name="crawlerThread" class="org.codelibs.fess.crawler.CrawlerThread" instance="prototype" >
	</component>

	<!-- Entity -->
	<component name="accessResult"

 * <p>
 * This package contains the data model classes that represent the structure of Maven POM files.
 * These classes are immutable to ensure thread safety and prevent unintended modifications.
 * The root class is {@link org.apache.maven.api.model.Model}, which represents the entire POM.
 * <p>
 * Key components include:
 * <ul>

        this.lock = new ReentrantReadWriteLock();

        // Start cleanup executor for expired leases
        this.cleanupExecutor = Executors.newSingleThreadScheduledExecutor(r -> {
            Thread t = new Thread(r, "LeaseManager-Cleanup");
            t.setDaemon(true);
            return t;
        });

        // Schedule periodic cleanup
        long cleanupInterval = context.getConfig().getLeaseTimeout();

 * invoke methods, they invoke methods on the {@code ForwardingSortedMultiset}.
 *
 * <p>The {@code standard} methods and any collection views they return are not guaranteed to be
 * thread-safe, even when all of the methods that they depend on are thread-safe.
 *
 * @author Louis Wasserman
 * @since 15.0
 */
@GwtCompatible
public abstract class ForwardingSortedMultiset<E extends @Nullable Object>

import org.apache.commons.pool2.impl.DefaultPooledObject;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.fess.crawler.container.CrawlerContainer;

/**
 * A thread-safe factory for creating and managing pooled crawler objects.
 * This class extends {@link BasePooledObjectFactory} and provides
 * methods for creating, wrapping, and destroying crawler components

        l2.forEach(l1::putIfAbsent);
        return l1;
    }

    // gather artifactIds which are not unique so that the respective thread names can be extended with the groupId
    public Set<String> duplicateIds() {
        if (duplicateIds == null) {
            synchronized (this) {
                if (duplicateIds == null) {