docs: public static <T> Collector<T, ?, DoubleMomentStatistics>
  	toDoubleMomentStatistics(final ToDoubleFunction<? super T> mapper) {
  		requireNonNull(mapper);
  		return Collector.of(
  			DoubleMomentStatistics::new,
  			(r, t) -> r.accept(mapper.applyAsDouble(t)),
  			DoubleMomentStatistics::combine
  		);
  	}