@SuppressWarnings("deprecation")
    public Event getEvent () throws MalformedEventException {
        if ((level == LogLevel.EVENT) && (event == null)) {
            try {
                event = Event.parse(getPayload());
                event.setTime(time.toEpochMilli());
            }
            catch (MalformedEventException e) {
                log.log(LogLevel.DEBUG, "Got malformed event: " + getPayload());
                throw e;
            }
        }
        return event;
    }
If the LogMessage was an EVENT then this method can
be used to get the Event instance representing the
event.  The event instance created the first time
this method is called and then cached.

TODO: make sure this throws exception!

@return Returns Event instance if this is an event message
        and the payload is correctly formatted.  Otherwise
        it will return <code>null</code>.
vespalog/src/main/java/com/yahoo/log/LogMessage.java