code: public RecurrenceId setRecurrenceId(Date originalStartDate) {
  		RecurrenceId prop = (originalStartDate == null) ? null : new RecurrenceId(originalStartDate);
  		setRecurrenceId(prop);
  		return prop;
  	}
docs: Sets the original value of the {@link DateStart} property if the journal
  entry is recurring and has been modified. Used in conjunction with the
  {@link Uid} and {@link Sequence} properties to uniquely identify a
  recurrence instance.
  @param originalStartDate the original start date or null to remove
  @return the property that was created
  @see <a href="http://tools.ietf.org/html/rfc5545#page-112">RFC 5545
  p.112-4</a>
  @see <a href="http://tools.ietf.org/html/rfc2445#page-107">RFC 2445
  p.107-9</a>