code: private String publishAll(KeenProject project,
                                Map<String, List<Map<String, Object>>> events) throws IOException {
          // just using basic JDK HTTP library
          String urlString = String.format(Locale.US, "%s/%s/projects/%s/events", getBaseUrl(),
                  KeenConstants.API_VERSION, project.getProjectId());
          URL url = new URL(urlString);
          return publishObject(project, url, events);
      }
docs: Publishes a batch of events to the Keen service.
  
  @param project The project in which to publish the event.
  @param events  A map from collection name to a list of event maps.
  @return The response from the server.
  @throws IOException If there was an error communicating with the server.