code: public void sendToUser(String topicURI, Object event, String eligibleUser) {
  		sendToUsers(topicURI, event, Collections.singleton(eligibleUser));
  	}
docs: Send an {@link EventMessage} to one client that is subscribed to the given
  topicURI. If the client with the given user name is not subscribed to the topicURI
  nothing happens.
  
  @param topicURI the name of the topic
  @param event the payload of the {@link EventMessage}
  @param eligibleUser only the user listed here will receive the message