return new MultimapBuilderWithKeys<@Nullable Object>() {
      @Override
      <K extends @Nullable Object, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
        return Platform.newLinkedHashMapWithExpectedSize(expectedKeys);
      }
    };
  }

  /**
   * Uses a naturally-ordered {@link TreeMap} to map keys to value collections.
   *