public final Set<ilarkesto.base.time.Date> getReleaseDates() { if (releaseDatesCache == null) { releaseDatesCache = new HashSet<ilarkesto.base.time.Date>(); for (Release e : getEntities()) { if (e.isReleaseDateSet()) releaseDatesCache.add(e.getReleaseDate()); } } return releaseDatesCache; }