return new WrappedSet(key, (Set<V>) collection);
      } else {
        return new WrappedCollection(key, collection, null);
      }
    }

    // can't use Serialization writeMultimap and populateMultimap methods since
    // there's no way to generate the empty backing map.

    /**
     * @serialData the factory and the backing map
     */
    @GwtIncompatible

        return new WrappedSet(key, (Set<V>) collection);
      } else {
        return new WrappedCollection(key, collection, null);
      }
    }

    // can't use Serialization writeMultimap and populateMultimap methods since
    // there's no way to generate the empty backing map.

    /**
     * @serialData the factory and the backing map
     */
    @GwtIncompatible

    public boolean isEmpty() {
      return MapMakerInternalMap.this.isEmpty();
    }

    @Override
    public void clear() {
      MapMakerInternalMap.this.clear();
    }
  }

  // Serialization Support

  private static final long serialVersionUID = 5;

  Object writeReplace() {
    return new SerializationProxy<>(
        entryHelper.keyStrength(),
        entryHelper.valueStrength(),