partitioningBy를 사용한 쪼개기 분할하기

Map<Boolean, Dish> mostCaloricPartitionedByVegetarian =
menu.stream().collect(
partitioningBy(Dish::isVegetarian,
collectingAndThen(maxBy(comparingInt(Dish::getCalories)),
Optional::get)));

결과는 {false=pork, true=pizza}