code: private String publish(KeenProject project, String eventCollection, Map<String, Object> event) throws IOException {
          URL url = createURL(project, eventCollection);
          if (url == null) {
              throw new IllegalStateException("URL address is empty");
          }
          return publishObject(project, url, event);
      }
docs: Publishes a single event to the Keen service.
  
  @param project         The project in which to publish the event.
  @param eventCollection The name of the collection in which to publish the event.
  @param event           The event to publish.
  @return The response from the server.
  @throws IOException If there was an error communicating with the server.