code: public static <I, K, V, O, R> String start(
        MapReduceSpecification<I, K, V, O, R> specification, MapReduceSettings settings) {
      if (settings.getWorkerQueueName() == null) {
        settings = new MapReduceSettings.Builder(settings).setWorkerQueueName("default").build();
      }
      PipelineService pipelineService = PipelineServiceFactory.newPipelineService();
      return pipelineService.startNewPipeline(
          new MapReduceJob<>(specification, settings), settings.toJobSettings());
    }
docs: Starts a {@link MapReduceJob} with the given parameters in a new Pipeline.
  Returns the pipeline id.