long estimatedSize = 0L;
    ImmutableList.Builder<Spliterator.OfDouble> splitrsBuilder =
        new ImmutableList.Builder<>(streams.length);
    for (DoubleStream stream : streams) {
      isParallel |= stream.isParallel();
      Spliterator.OfDouble splitr = stream.spliterator();
      splitrsBuilder.add(splitr);
      characteristics &= splitr.characteristics();

    long estimatedSize = 0L;
    ImmutableList.Builder<Spliterator.OfDouble> splitrsBuilder =
        new ImmutableList.Builder<>(streams.length);
    for (DoubleStream stream : streams) {
      isParallel |= stream.isParallel();
      Spliterator.OfDouble splitr = stream.spliterator();
      splitrsBuilder.add(splitr);
      characteristics &= splitr.characteristics();

  }

  /**
   * @since NEXT (but since 28.1 in the JRE flavor)
   */
  public static SpliteratorTester<Double> ofDouble(
      Supplier<Spliterator.OfDouble> spliteratorSupplier) {
    return new SpliteratorTester<>(
        ImmutableSet.of(
            () -> new GeneralSpliteratorOfObject<>(spliteratorSupplier.get()),

  }

  /**
   * @since 28.1 (but only since 33.4.0 in the Android flavor)
   */
  public static SpliteratorTester<Double> ofDouble(
      Supplier<Spliterator.OfDouble> spliteratorSupplier) {
    return new SpliteratorTester<>(
        ImmutableSet.of(
            () -> new GeneralSpliteratorOfObject<>(spliteratorSupplier.get()),

                    Spliterator.SIZED | Spliterator.DISTINCT | Spliterator.NONNULL,
                    4))
        .expect(1L, 1L, 2L, 3L);
  }

  public void testFlatMapToDouble_nullStream() {
    SpliteratorTester.ofDouble(
            () ->
                CollectSpliterators.flatMapToDouble(
                    Arrays.spliterator(new Double[] {1.0, 0.0, 1.0, 2.0, 3.0}),