checkNotNull(elements);
      if (elements instanceof Collection) {
        Collection<?> collection = (Collection<?>) elements;
        ensureRoomFor(collection.size());
        if (collection instanceof ImmutableCollection) {
          ImmutableCollection<?> immutableCollection = (ImmutableCollection<?>) collection;
          size = immutableCollection.copyIntoArray(contents, size);
          return this;

import com.google.j2objc.annotations.Weak;
import com.google.j2objc.annotations.WeakOuter;
import java.util.AbstractQueue;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.PriorityQueue;

  static boolean removeAllImpl(Multiset<?> self, Collection<?> elementsToRemove) {
    Collection<?> collection =
        (elementsToRemove instanceof Multiset)
            ? ((Multiset<?>) elementsToRemove).elementSet()
            : elementsToRemove;

    return self.elementSet().removeAll(collection);
  }

  /** An implementation of {@link Multiset#retainAll}. */

import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;

 * the License.
 */

package com.google.common.base;

import static com.google.common.base.Preconditions.checkNotNull;
import static java.util.Arrays.asList;
import static java.util.Collections.unmodifiableList;
import static java.util.Objects.requireNonNull;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

import com.google.common.collect.testing.TestStringSortedMapGenerator;
import java.util.List;
import java.util.Map.Entry;
import java.util.SortedMap;

/**
 * Generators of sorted maps and derived collections.
 *
 * @author Kevin Bourrillion
 * @author Jesse Wilson
 * @author Jared Levy
 * @author Hayward Chan
 * @author Chris Povirk
 * @author Louis Wasserman
 */
@GwtCompatible

 */

package com.google.common.collect.testing;

import static com.google.common.collect.testing.Helpers.castOrCopyToList;
import static com.google.common.collect.testing.Helpers.copyToList;
import static java.util.Collections.reverse;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.collect.testing.DerivedCollectionGenerators.Bound;

import com.google.common.testing.ClassSanityTester;
import com.google.common.util.concurrent.MoreExecutors.Application;
import java.lang.Thread.State;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;

import java.io.ObjectOutputStream;
import java.lang.reflect.Field;
import java.util.Collection;
import java.util.Map;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Provides static methods for serializing collection classes.
 *
 * <p>This class assists the implementation of collection classes. Do not use this class to
 * serialize collections that are defined elsewhere.
 *
 * @author Jared Levy
 */
@GwtIncompatible

  }

  /**
   * Adapts an {@code Iterator} to the {@code Enumeration} interface.
   *
   * <p>The {@code Iterable} equivalent of this method is either {@link Collections#enumeration} (if
   * you have a {@link Collection}), or {@code Iterators.asEnumeration(collection.iterator())}.
   */
  public static <T extends @Nullable Object> Enumeration<T> asEnumeration(Iterator<T> iterator) {
    checkNotNull(iterator);