code: public RecurrenceRule setRecurrenceRule(Recurrence recur) {
  		RecurrenceRule prop = (recur == null) ? null : new RecurrenceRule(recur);
  		setRecurrenceRule(prop);
  		return prop;
  	}
docs: Sets how often the journal entry repeats.
  @param recur the recurrence rule or null to remove
  @return the property that was created
  @see <a href="http://tools.ietf.org/html/rfc5545#page-122">RFC 5545
  p.122-32</a>
  @see <a href="http://tools.ietf.org/html/rfc2445#page-117">RFC 2445
  p.117-25</a>