code: public FreeBusyType getFreeBusyType() {
  		String value = first(FBTYPE);
  		return (value == null) ? null : FreeBusyType.get(value);
  	}
docs: <p>
  Gets the FBTYPE (free busy type) parameter value.
  </p>
  <p>
  This parameter is used by the {@link FreeBusy} property. It defines
  whether the person is "free" or "busy" over the time periods that are
  specified in the property value. If this parameter is not set, the user
  should be considered "busy" during these times.
  </p>
  @return the free busy type or null if not set
  @see <a href="http://tools.ietf.org/html/rfc5545#page-20">RFC 5545
  p.20</a>