docs: private static BigDecimal calculateProrationBetweenDates(final LocalDate startDate, final LocalDate endDate, final LocalDate previousBillingCycleDate, final LocalDate nextBillingCycleDate) {
          final int daysBetween = Days.daysBetween(previousBillingCycleDate, nextBillingCycleDate).getDays();
          return calculateProrationBetweenDates(startDate, endDate, daysBetween);
      }