Solutionunvalidated
You can use `Collectors.collectingAndThen`, but then you need to keep a list of the grouped values so you can access the nail index later — Collectors.collectingAndThen. Tension: you need to keep a list of the grouped values so you can access the nail index later.
17d244ae-6e53-4f22-9215-523f0b08380e
You can use Collectors.collectingAndThen, but then you need to keep a list of the grouped values so you can access the nail index later — Collectors.collectingAndThen. Tension: you need to keep a list of the grouped values so you can access the nail index later.