}

  static <K extends @Nullable Object, V extends @Nullable Object> Multimap<K, V> multimap(
      Multimap<K, V> multimap, @Nullable Object mutex) {
    if (multimap instanceof SynchronizedMultimap || multimap instanceof BaseImmutableMultimap) {
      return multimap;
    }
    return new SynchronizedMultimap<>(multimap, mutex);
  }

import java.util.Map.Entry;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A set multimap which forwards all its method calls to another set multimap. Subclasses should
 * override one or more methods to modify the behavior of the backing multimap as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

 * implementation.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public class MultimapTestSuiteBuilder<K, V, M extends Multimap<K, V>>
    extends PerCollectionSizeTestSuiteBuilder<
        MultimapTestSuiteBuilder<K, V, M>, TestMultimapGenerator<K, V, M>, M, Entry<K, V>> {

  public static <K, V, M extends Multimap<K, V>> MultimapTestSuiteBuilder<K, V, M> using(

import java.util.Comparator;
import java.util.SortedSet;
import org.jspecify.annotations.Nullable;

/**
 * A sorted set multimap which forwards all its method calls to another sorted set multimap.
 * Subclasses should override one or more methods to modify the behavior of the backing multimap as
 * desired per the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.List;
import org.jspecify.annotations.Nullable;

/**
 * A list multimap which forwards all its method calls to another list multimap. Subclasses should
 * override one or more methods to modify the behavior of the backing multimap as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

import java.util.Comparator;
import java.util.SortedSet;
import org.jspecify.annotations.Nullable;

/**
 * A sorted set multimap which forwards all its method calls to another sorted set multimap.
 * Subclasses should override one or more methods to modify the behavior of the backing multimap as
 * desired per the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

    HashMultimap<K, V> multimap = HashMultimap.create();
    multimap.put(key, value);
    return multimap;
  }

  @Generates
  static <K, V> LinkedHashMultimap<K, V> generateLinkedHashMultimap(
      @Nullable K key, @Nullable V value) {
    LinkedHashMultimap<K, V> multimap = LinkedHashMultimap.create();
    multimap.put(key, value);
    return multimap;
  }

  @Generates

  public void testPutAllAddsAtEndInOrder() {
    List<V> values = asList(v3(), v1(), v4());

    for (K k : sampleKeys()) {
      resetContainer();

      List<V> expectedValues = copyToList(multimap().get(k));

      assertTrue(multimap().putAll(k, values));
      expectedValues.addAll(values);

      assertGet(k, expectedValues);
    }
  }

  public void testPutAllHandlesDuplicates() {
    List<V> valuesToPut = asList(v0(), v1(), v0());

    for (K k : sampleKeys()) {
      resetContainer();

      Set<V> expectedValues = copyToSet(multimap().get(k));

      multimap().putAll(k, valuesToPut);
      expectedValues.addAll(valuesToPut);

      assertGet(k, expectedValues);
    }
  }

import com.google.common.collect.testing.MapInterfaceTest;
import java.util.Collection;
import java.util.Map;
import org.jspecify.annotations.NullMarked;

/**
 * Test {@link Multimap#asMap()} for an {@link ImmutableMultimap} with {@link MapInterfaceTest}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@NullMarked
public class ImmutableMultimapAsMapImplementsMapTest