* JdkBackedSetBuilderImpl.
   */
  private static final class RegularSetBuilderImpl<E> extends SetBuilderImpl<E> {
    // null until at least two elements are present
    private @Nullable Object @Nullable [] hashTable;
    private int maxRunBeforeFallback;
    private int expandTableThreshold;
    private int hashCode;

    RegularSetBuilderImpl(int expectedCapacity) {
      super(expectedCapacity);