* key-value mapping appears multiple times in the input multimap, it only appears once in the
   * constructed multimap.
   *
   * <p>This method will soon be deprecated in favor of {@code
   * MultimapBuilder.hashKeys().hashSetValues().build(multimap)}.
   *
   * @param multimap the multimap whose contents are copied to this multimap
   */

    checkNotNull(multimapSupplier);
    return Collector.of(
        multimapSupplier,
        (multimap, input) -> multimap.put(keyFunction.apply(input), valueFunction.apply(input)),
        (multimap1, multimap2) -> {
          multimap1.putAll(multimap2);
          return multimap1;
        });
  }

  static <
          T extends @Nullable Object,
          K extends @Nullable Object,

import com.google.common.base.Predicate;
import java.util.Map.Entry;
import java.util.Set;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@link Multimaps#filterKeys(SetMultimap, Predicate)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
final class FilteredKeySetMultimap<K extends @Nullable Object, V extends @Nullable Object>

    checkNotNull(multimapSupplier);
    return Collector.of(
        multimapSupplier,
        (multimap, input) -> multimap.put(keyFunction.apply(input), valueFunction.apply(input)),
        (multimap1, multimap2) -> {
          multimap1.putAll(multimap2);
          return multimap1;
        });
  }

  static <
          T extends @Nullable Object,
          K extends @Nullable Object,

   */
  static <K extends @Nullable Object, V extends @Nullable Object> void writeMultimap(
      Multimap<K, V> multimap, ObjectOutputStream stream) throws IOException {
    stream.writeInt(multimap.asMap().size());
    for (Map.Entry<K, Collection<V>> entry : multimap.asMap().entrySet()) {
      stream.writeObject(entry.getKey());
      stream.writeInt(entry.getValue().size());

/**
 * Implementation of {@link Multimaps#filterKeys(Multimap, Predicate)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
class FilteredKeyMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
  final Multimap<K, V> unfiltered;
  final Predicate<? super K> keyPredicate;

/**
 * Implementation of {@link Multimaps#filterKeys(Multimap, Predicate)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
class FilteredKeyMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
  final Multimap<K, V> unfiltered;
  final Predicate<? super K> keyPredicate;

import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.MultimapBuilder;
import com.google.common.collect.Multimaps;
import com.google.common.collect.Multiset;
import com.google.common.collect.Ordering;
import com.google.common.collect.SetMultimap;
import com.google.common.util.concurrent.Service.State;

   *
   * <p>This method will soon be deprecated in favor of {@code
   * MultimapBuilder.hashKeys().arrayListValues().build(multimap)}.
   *
   * @param multimap the multimap whose contents are copied to this multimap
   */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      ArrayListMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {

import com.google.common.collect.Iterators;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.MapDifference;
import com.google.common.collect.Maps;
import com.google.common.collect.Multimap;
import com.google.common.collect.Multimaps;
import com.google.common.collect.Multiset;
import com.google.common.collect.Ordering;
import com.google.common.collect.PeekingIterator;
import com.google.common.collect.Range;