}

  static <E extends @Nullable Object> Deque<E> deque(Deque<E> deque, @Nullable Object mutex) {
    return new SynchronizedDeque<>(deque, mutex);
  }

  static final class SynchronizedDeque<E extends @Nullable Object> extends SynchronizedQueue<E>
      implements Deque<E> {

    SynchronizedDeque(Deque<E> delegate, @Nullable Object mutex) {
      super(delegate, mutex);
    }

  }

  static <E extends @Nullable Object> Deque<E> deque(Deque<E> deque, @Nullable Object mutex) {
    return new SynchronizedDeque<>(deque, mutex);
  }

  static final class SynchronizedDeque<E extends @Nullable Object> extends SynchronizedQueue<E>
      implements Deque<E> {

    SynchronizedDeque(Deque<E> delegate, @Nullable Object mutex) {
      super(delegate, mutex);
    }

import java.nio.ShortBuffer;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.Collection;
import java.util.Comparator;
import java.util.Currency;
import java.util.Deque;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.Locale;
import java.util.Map;

import java.nio.ShortBuffer;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.Collection;
import java.util.Comparator;
import java.util.Currency;
import java.util.Deque;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.Locale;
import java.util.Map;

import org.jspecify.annotations.Nullable;

/**
 * A {@link BlockingDeque} which forwards all its method calls to another {@code BlockingDeque}.
 * Subclasses should override one or more methods to modify the behavior of the backing deque as
 * desired per the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingBlockingDeque} forward <b>indiscriminately</b>

import java.nio.ShortBuffer;
import java.nio.charset.Charset;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.Currency;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Locale;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;

import java.nio.ShortBuffer;
import java.nio.charset.Charset;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.Currency;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Locale;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;

import com.google.errorprone.annotations.InlineMe;
import com.google.errorprone.annotations.InlineMeValidationDisabled;
import java.util.ArrayDeque;
import java.util.Collection;
import java.util.Deque;
import java.util.Iterator;
import java.util.OptionalDouble;
import java.util.OptionalInt;
import java.util.OptionalLong;
import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.Spliterators;

 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.ds.callback;

import static org.codelibs.core.stream.StreamUtil.stream;

import java.util.ArrayList;
import java.util.Deque;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.ExecutorService;

    }

    /**
     * Creates and returns a new instance of {@link ArrayDeque}.
     *
     * @param <E> the element type of {@link ArrayDeque}
     * @param c the collection of elements to be placed in the deque
     * @return a new instance of {@link ArrayDeque}
     * @see ArrayDeque#ArrayDeque(Collection)
     */
    public static <E> ArrayDeque<E> newArrayDeque(final Collection<? extends E> c) {