public String eventTopic(String eventId){
  if (eventId == null) {
    eventId="+";
  }
  return evtTopic.replace("{EVENTID}",eventId);
}

public String eventTopic ( String eventId ) { if ( eventId == null ) { eventId = "+" ; } return evtTopic . replace ( "{EVENTID}" , eventId ) ; }
get the mqtt topic for an device event .
