code: protected final void addChrstianHoliday (final ChronoLocalDate aDate,
                                             final String sPropertiesKey,
                                             final IHolidayType aHolidayType,
                                             final HolidayMap holidays)
    {
      final LocalDate convertedDate = LocalDate.from (aDate);
      holidays.add (convertedDate, new ResourceBundleHoliday (aHolidayType, sPropertiesKey));
    }
docs: Adds the given day to the list of holidays.
  
  @param aDate
  The day
  @param sPropertiesKey
  a {@link java.lang.String} object.
  @param aHolidayType
  a {@link HolidayType} object.
  @param holidays
  a {@link java.util.Set} object.