private static class UnmodifiableMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends ForwardingMultimap<K, V> implements Serializable {
    final Multimap<K, V> delegate;
    @LazyInit transient @Nullable Collection<Entry<K, V>> entries;
    @LazyInit transient @Nullable Multiset<K> keys;
    @LazyInit transient @Nullable Set<K> keySet;
    @LazyInit transient @Nullable Collection<V> values;

  private static class UnmodifiableMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends ForwardingMultimap<K, V> implements Serializable {
    final Multimap<K, V> delegate;
    @LazyInit transient @Nullable Collection<Entry<K, V>> entries;
    @LazyInit transient @Nullable Multiset<K> keys;
    @LazyInit transient @Nullable Set<K> keySet;
    @LazyInit transient @Nullable Collection<V> values;

    }

    @Override
    public boolean containsKey(@Nullable Object key) {
      return backingSet().contains(key);
    }

    @Override
    public @Nullable V get(@Nullable Object key) {
      return getOrDefault(key, null);
    }

    @Override
    public @Nullable V getOrDefault(@Nullable Object key, @Nullable V defaultValue) {
      if (Collections2.safeContains(backingSet(), key)) {

  }

  private static <K extends @Nullable Object, V extends @Nullable Object>
      @Nullable Entry<K, V> unmodifiableOrNull(@Nullable Entry<K, ? extends V> entry) {
    return (entry == null) ? null : unmodifiableEntry(entry);
  }

  @GwtIncompatible // NavigableMap
  private static final class UnmodifiableNavigableMap<
          K extends @Nullable Object, V extends @Nullable Object>

   * @since 11.0
   */
  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
      Table<R, C, V> unmodifiableTable(Table<? extends R, ? extends C, ? extends V> table) {
    return new UnmodifiableTable<>(table);
  }

  private static class UnmodifiableTable<
          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>

    }

    @Override
    @Nullable C correctedDoForward(@Nullable A a) {
      return second.correctedDoForward(first.correctedDoForward(a));
    }

    @Override
    @Nullable A correctedDoBackward(@Nullable C c) {
      return first.correctedDoBackward(second.correctedDoBackward(c));
    }

    @Override
    public boolean equals(@Nullable Object object) {

   */
  // TODO(kevinb): copy to Comparators, etc.
  @J2ktIncompatible // MapMaker
  public static Ordering<@Nullable Object> arbitrary() {
    return ArbitraryOrderingHolder.ARBITRARY_ORDERING;
  }

  @J2ktIncompatible // MapMaker
  private static final class ArbitraryOrderingHolder {
    static final Ordering<@Nullable Object> ARBITRARY_ORDERING = new ArbitraryOrdering();
  }

  @J2ktIncompatible // MapMaker

  private static class SynchronizedMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends SynchronizedObject implements Multimap<K, V> {
    transient @Nullable Set<K> keySet;
    transient @Nullable Collection<V> valuesCollection;
    transient @Nullable Collection<Map.Entry<K, V>> entries;
    transient @Nullable Map<K, Collection<V>> asMap;
    transient @Nullable Multiset<K> keys;

    @SuppressWarnings("unchecked")

  private static class SynchronizedMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends SynchronizedObject implements Multimap<K, V> {
    transient @Nullable Set<K> keySet;
    transient @Nullable Collection<V> valuesCollection;
    transient @Nullable Collection<Map.Entry<K, V>> entries;
    transient @Nullable Map<K, Collection<V>> asMap;
    transient @Nullable Multiset<K> keys;

    @SuppressWarnings("unchecked")

            """
        ) {
            assertHasNoError()
            assertHasWarnings(
                "Field finalField: Nullability changed from nullable to non-nullable",
                "Method com.example.Source.foo(java.lang.String): Return nullability changed from nullable to non-nullable"
            )
            assertHasNoInformation()
        }
    }

    @Test