code: public void emit(String name, Tree payload) {
  		eventbus.emit(name, payload, null, false);
  	}
docs: Emits an event to <b>ONE</b> listener from ALL event groups, who are
  listening this event. The service broker uses the default {@link Strategy
  strategy} of the broker for event redirection and node selection. Sample
  code:<br>
  <br>
  Tree params = new Tree();<br>
  params.put("a", true);<br>
  params.putList("b").add(1).add(2).add(3);<br>
  ctx.emit("user.modified", params);
  
  @param name
  name of event (eg. "user.created")
  @param payload
  {@link Tree} structure (payload of the event)