* #writeMultimap} for the data format.
   */
  static <K extends @Nullable Object, V extends @Nullable Object> void populateMultimap(
      Multimap<K, V> multimap, ObjectInputStream stream)
      throws IOException, ClassNotFoundException {
    int distinctKeys = stream.readInt();
    populateMultimap(multimap, stream, distinctKeys);
  }

  /**

    stream.defaultReadObject();
    expectedValuesPerKey = DEFAULT_VALUES_PER_KEY;
    int distinctKeys = stream.readInt();
    Map<K, Collection<V>> map = new HashMap<>();
    setMap(map);
    Serialization.populateMultimap(this, stream, distinctKeys);
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

    valueComparator = requireNonNull((Comparator<? super V>) stream.readObject());
    setMap(new TreeMap<K, Collection<V>>(keyComparator));
    Serialization.populateMultimap(this, stream);
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

        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
    @J2ktIncompatible