Multimap<K, V> synchronizedMultimap(Multimap<K, V> multimap) {
    return Synchronized.multimap(multimap, null);
  }

  /**
   * Returns an unmodifiable view of the specified multimap. Query operations on the returned
   * multimap "read through" to the specified multimap, and attempts to modify the returned
   * multimap, either directly or through the multimap's views, result in an {@code

    multimap.put("bar", 5);
    multimap.put("bar", -1);
    multimap.put(nullKey, nullValue);
    multimap.put("foo", nullValue);
    multimap.put(nullKey, 5);
    multimap.put("foo", 2);

    if (permitsDuplicates) {
      assertEquals(9, multimap.size());
    } else {
      assertEquals(8, multimap.size());
    }

    Multimap<@Nullable String, @Nullable Integer> unmodifiable;

                  @Override
                  Multimap<String, String> transform(Multimap<String, String> multimap) {
                    return Multimaps.transformEntries(multimap, ENTRY_TRANSFORMER);
                  }
                })
            .named("Multimaps.transformEntries[Multimap]")
            .withFeatures(
                CollectionSize.ANY,
                MapFeature.SUPPORTS_REMOVE,

                  @Override
                  Multimap<String, String> transform(Multimap<String, String> multimap) {
                    return Multimaps.transformEntries(multimap, ENTRY_TRANSFORMER);
                  }
                })
            .named("Multimaps.transformEntries[Multimap]")
            .withFeatures(
                CollectionSize.ANY,
                MapFeature.SUPPORTS_REMOVE,

import static com.google.common.collect.Multimaps.filterKeys;
import static com.google.common.collect.Multimaps.filterValues;
import static java.util.Arrays.asList;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Predicate;
import java.util.Map.Entry;
import junit.framework.TestCase;

/**
 * Unit tests for {@link Multimaps} filtering methods.
 *
 * @author Jared Levy
 */

    return Multimaps.transformValues(
            ArrayListMultimap.<String, Integer>create(), Functions.<Integer>identity())
        .asMap();
  }

  @Override
  protected Map<String, Collection<Integer>> makePopulatedMap() {
    ListMultimap<String, Integer> delegate = ArrayListMultimap.create();
    populate(delegate);

import static com.google.common.collect.Multimaps.filterKeys;
import static com.google.common.collect.Multimaps.filterValues;
import static java.util.Arrays.asList;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Predicate;
import java.util.Map.Entry;
import junit.framework.TestCase;

/**
 * Unit tests for {@link Multimaps} filtering methods.
 *
 * @author Jared Levy
 */

   *
   * <p>The collections returned by {@link Multimap#keySet()}, {@link Multimap#keys()}, and {@link
   * Multimap#asMap()} will iterate through the keys in sorted order.
   *
   * <p>For all multimaps generated by the resulting builder, the {@link Multimap#keySet()} can be
   * safely cast to a {@link java.util.SortedSet}, and the {@link Multimap#asMap()} can safely be
   * cast to a {@link java.util.SortedMap}.
   */

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.MapInterfaceTest;
import java.util.Collection;
import java.util.Map;

/**
 * Test {@link Multimap#asMap()} for a {@link Multimaps#forMap} multimap with {@link
 * MapInterfaceTest}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

   *
   * @throws NullPointerException if any key or value in {@code multimap} is null
   */
  public static <K, V> ImmutableListMultimap<K, V> copyOf(
      Multimap<? extends K, ? extends V> multimap) {
    if (multimap.isEmpty()) {
      return of();
    }

    // TODO(lowasser): copy ImmutableSetMultimap by using asList() on the sets
    if (multimap instanceof ImmutableListMultimap) {