code: @Programmatic
      public Collection<String> calendarNamesFor(final Object notable) {
          final Set<String> fallback = Collections.singleton(DEFAULT_CALENDAR_NAME);
          if(calendarNameRepository == null) {
              return fallback;
          }
          final Collection<String> calendarNames = calendarNameRepository.calendarNamesFor(notable);
          return calendarNames != null? calendarNames: fallback;
      }
docs: Return the list of objects to act as calendars for the {@link Note}s to attach to the specified "notable"
  domain object, as per {@link CalendarNameRepository}, or a default name otherwise.
  
  <p>
  May return null if there are none (in which case a default name will be used).
  </p>