code: public ExceptionRule addExceptionRule(Recurrence recur) {
  		ExceptionRule prop = new ExceptionRule(recur);
  		addExceptionRule(prop);
  		return prop;
  	}
docs: <p>
  Adds an exception for the {@link RecurrenceRule} property.
  </p>
  <p>
  Note that this property has been removed from the latest version of the
  iCal specification. Its use should be avoided.
  </p>
  @param recur the exception rule to add
  @return the property that was created
  @see <a href="http://tools.ietf.org/html/rfc2445#page-114">RFC 2445
  p.114-15</a>