util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see
    https://groups.google.com/g/google-web-toolkit-contributors/c/CqYH59Dt_rQ/m/uVGW1QdUsXUJ
    for details.

    The summary is that it ignores one file in favor of the other.
    util.concurrent, like nearly all our packages, has two .gwt.xml files: one

import static com.google.common.collect.testing.features.CollectionFeature.KNOWN_ORDER;
import static java.util.Arrays.asList;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractCollectionTester;
import com.google.common.collect.testing.features.CollectionFeature;
import java.util.ArrayList;
import java.util.List;
import org.junit.Ignore;

/**

import java.security.SecurityPermission;
import java.util.Date;
import java.util.NoSuchElementException;
import java.util.PropertyPermission;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.RejectedExecutionHandler;

import com.google.common.collect.testing.features.MapFeature;
import java.lang.reflect.Method;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;
import org.junit.Ignore;

/**

import com.google.common.annotations.GwtIncompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.EnumSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.stream.Stream;
import org.jspecify.annotations.NullUnmarked;

@GwtIncompatible
@NullUnmarked

 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.crawler.service.impl;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Queue;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.core.lang.StringUtil;
import org.codelibs.core.lang.SystemUtil;

import java.io.Serializable;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.Set;
import java.util.Spliterator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.function.ToIntFunction;

import java.time.Instant;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.ReadWriteLock;

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.util;

import org.dbflute.optional.OptionalEntity;

/**
 * Utility class for Optional operations.
 */
public class OptionalUtil {

    /**
     * Default constructor.
     */
    private OptionalUtil() {

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

package com.google.common.collect.testing;

import com.google.common.annotations.GwtCompatible;
import java.util.Iterator;

/**
 * Adapts a test iterable generator to give a TestIteratorGenerator.
 *
 * @author George van den Driessche
 */
@GwtCompatible
public final class DerivedTestIteratorGenerator<E>