import java.io.InterruptedIOException
import java.util.concurrent.CountDownLatch
import java.util.concurrent.TimeUnit
import java.util.concurrent.atomic.AtomicInteger
import kotlin.test.assertFailsWith
import okhttp3.Headers
import okhttp3.Headers.Companion.headersOf
import okhttp3.TestUtil.headerEntries
import okhttp3.TestUtil.repeat
import okhttp3.internal.EMPTY_BYTE_ARRAY
import okhttp3.internal.concurrent.Lockable

 * under the License.
 */
package org.apache.maven.artifact.deployer;

import javax.inject.Inject;
import javax.inject.Named;

import java.io.File;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.maven.RepositoryUtils;
import org.apache.maven.artifact.Artifact;
import org.apache.maven.artifact.metadata.ArtifactMetadata;

package org.apache.maven.plugin;

import javax.inject.Named;
import javax.inject.Singleton;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.maven.RepositoryUtils;
import org.apache.maven.model.Plugin;
import org.apache.maven.plugin.descriptor.PluginDescriptor;
import org.eclipse.aether.RepositorySystemSession;

 */
@GwtCompatible
@IgnoreJRERequirement // Users will use this only if they're already using streams.
public final class MoreCollectors {

  /*
   * TODO(lowasser): figure out if we can convert this to a concurrent AtomicReference-based
   * collector without breaking j2cl?
   */
  private static final Collector<Object, ?, Optional<Object>> TO_OPTIONAL =
      Collector.of(
          ToOptionalState::new,

Guava is a set of core Java libraries from Google that includes new collection
types (such as multimap and multiset), immutable collections, a graph library,
and utilities for concurrency, I/O, hashing, primitives, strings, and more! It
is widely used on most Java projects within Google, and widely used by many
other companies as well.



Guava comes in two flavors:

import java.util.NavigableSet;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;
import java.util.regex.MatchResult;
import java.util.regex.Pattern;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**

    printEvent("callStart");
  }

  @Override public void callEnd(Call call) {
    printEvent("callEnd");
  }

  ...
}
```

We can use this listener to race a pair of concurrent HTTP requests:

```java
Request washingtonPostRequest = new Request.Builder()
    .url("https://www.washingtonpost.com/")
    .build();
client.newCall(washingtonPostRequest).enqueue(new Callback() {
  ...

package org.codelibs.fess.filter;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.net.URLCodec;
import org.codelibs.core.lang.StringUtil;
import org.lastaflute.web.servlet.filter.LastaPrepareFilter;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tester to ensure forwarding wrapper works by delegating calls to the corresponding method with

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package jcifs.internal.witness;

import java.net.InetAddress;
import java.util.concurrent.atomic.AtomicLong;

/**
 * Represents a witness service registration for SMB resource monitoring.
 * This class maintains registration state, heartbeat information, and