@Test
void spliteratorEstimateSize() {

    final AtomicInteger cnt = new AtomicInteger();
    final Spliterator<String> spliterator = instance.spliterator();
    assertEquals(1, spliterator.estimateSize());
    spliterator.tryAdvance(e -> cnt.incrementAndGet());
    assertEquals(0, spliterator.estimateSize());
    assertEquals(1, cnt.get());
}