"estimated size of trySplit result (%s) is larger than original size (%s)",
                trySplit.estimateSize(), originalSize));
      }
    }
    if (subsized) {
      if (trySplit != null) {
        assertEquals(
            "sum of estimated sizes of trySplit and original spliterator after trySplit",
            originalSize,
            trySplit.estimateSize() + spliterator.estimateSize());
      } else {

      this.fromSpliterator = fromSpliterator;
      this.index = index;
    }

    abstract S createSplit(F from, long i);

    @Override
    public @Nullable S trySplit() {
      Spliterator<?> splitOrNull = fromSpliterator.trySplit();
      if (splitOrNull == null) {
        return null;
      }
      @SuppressWarnings("unchecked")
      F split = (F) splitOrNull;
      S result = createSplit(split, index);