// GWT's ConcurrentHashMap is a wrapper around HashMap, but it rejects null keys, which matches
    // the behaviour of the non-GWT implementation of newConcurrentHashSet().
    // On the other hand HashSet might be better for code size if apps aren't
    // already using Collections.newSetFromMap and ConcurrentHashMap.
    return Collections.newSetFromMap(new ConcurrentHashMap<E, Boolean>());
  }

  private final Set<HttpUrl> fetchedUrls = Collections.synchronizedSet(new LinkedHashSet<>());
  private final LinkedBlockingQueue<HttpUrl> queue = new LinkedBlockingQueue<>();
  private final ConcurrentHashMap<String, AtomicInteger> hostnames = new ConcurrentHashMap<>();

  public Crawler(OkHttpClient client) {
    this.client = client;
  }

  private void parallelDrainQueue(int threadCount) {

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

import java.nio.file.Path;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Stream;

import org.apache.maven.api.Artifact;
import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.di.SessionScoped;

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

import java.io.File;
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.artifact.Artifact;
import org.apache.maven.project.ExtensionDescriptor;
import org.apache.maven.project.MavenProject;
import org.codehaus.plexus.classworlds.realm.ClassRealm;

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

import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;

import org.apache.maven.api.JavaPathType;
import org.apache.maven.api.Type;
import org.apache.maven.api.annotations.Nonnull;

import org.codelibs.fess.util.JobProcess;

public class ProcessHelper {
    private static final Logger logger = LogManager.getLogger(ProcessHelper.class);

    protected final ConcurrentHashMap<String, JobProcess> runningProcessMap = new ConcurrentHashMap<>();

    protected int processDestroyTimeout = 10;

    @PreDestroy
    public void destroy() {
        for (final String sessionId : runningProcessMap.keySet()) {

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

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

import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.codehaus.plexus.classworlds.realm.NoSuchRealmException;
import org.codehaus.plexus.personality.plexus.lifecycle.phase.Disposable;

        Map<Element, Element> map = new ConcurrentHashMap<>(keys.size(), 0.75f, 1);
        for (Element element : keys) {
          map.put(element, element);
        }
        return map;
      }
    },
    ConcurrentHM16 {
      @Override
      Map<Element, Element> create(Collection<Element> keys) {
        Map<Element, Element> map = new ConcurrentHashMap<>(keys.size(), 0.75f, 16);

 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkArgument;

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * MapMaker emulation.
 *
 * @author Charles Fry
 */
@ElementTypesAreNonnullByDefault
public final class MapMaker {
  private int initialCapacity = 16;

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import junit.framework.TestCase;

/**
 * Tests for {@link ForwardingConcurrentMap}.
 *
 * @author Jared Levy
 */