The "PUBLISH" method in a "VEVENT" calendar component
is an unsolicited posting of an iCalendar object. Any CU may add published
components to their calendar. The "Organizer" MUST be present in
a published iCalendar component. "Attendees" MUST NOT be present.
Its expected usage is for encapsulating an arbitrary event as an iCalendar
object. The "Organizer" may subsequently update (with another
"PUBLISH" method), add instances to (with an "ADD"
method), or cancel (with a "CANCEL" method) a previously
published "VEVENT" calendar component.