code: public FreeBusy addFreeBusy(FreeBusyType type, Date start, Date end) {
  		FreeBusy found = findByFreeBusyType(type);
  		found.getValues().add(new Period(start, end));
  		return found;
  	}
docs: Adds a single time period for which the person is free or busy (for
  example, "free" between 1pm-3pm). This method will look for an existing
  property that has the given {@link FreeBusyType} and add the time period
  to it, or create a new property is one cannot be found.
  @param type the availability type (e.g. "free" or "busy")
  @param start the start date-time
  @param end the end date-time
  @return the property that was created/modified
  @see <a href="http://tools.ietf.org/html/rfc5545#page-100">RFC 5545
  p.100-1</a>
  @see <a href="http://tools.ietf.org/html/rfc2445#page-95">RFC 2445
  p.95-6</a>