private static JobTaskVertex createMapper(
      JobGraph jobGraph, int numSubTasks, TypeSerializerFactory<?> serializer) {
    JobTaskVertex pointsInput =
        JobGraphUtils.createTask(
            RegularPactTask.class, "Map[DotProducts]", jobGraph, numSubTasks, numSubTasks);

    {
      TaskConfig taskConfig = new TaskConfig(pointsInput.getConfiguration());

      taskConfig.setStubWrapper(new UserCodeClassWrapper<DotProducts>(DotProducts.class));
      taskConfig.addOutputShipStrategy(ShipStrategyType.FORWARD);
      taskConfig.setOutputSerializer(serializer);
      taskConfig.setDriver(CollectorMapDriver.class);
      taskConfig.setDriverStrategy(DriverStrategy.COLLECTOR_MAP);

      taskConfig.addInputToGroup(0);
      taskConfig.setInputLocalStrategy(0, LocalStrategy.NONE);
      taskConfig.setInputSerializer(serializer, 0);

      taskConfig.setBroadcastInputName("models", 0);
      taskConfig.addBroadcastInputToGroup(0);
      taskConfig.setBroadcastInputSerializer(serializer, 0);
    }

    return pointsInput;
  }
  private static JobTaskVertex createMapper(
      JobGraph jobGraph,
      int numSubTasks,
      TypeSerializerFactory<?> inputSerializer,
      TypeSerializerFactory<?> broadcastVarSerializer,
      TypeSerializerFactory<?> outputSerializer,
      TypeComparatorFactory<?> outputComparator) {
    JobTaskVertex mapper =
        JobGraphUtils.createTask(
            IterationIntermediatePactTask.class,
            "Map (Select nearest center)",
            jobGraph,
            numSubTasks,
            numSubTasks);

    TaskConfig intermediateConfig = new TaskConfig(mapper.getConfiguration());
    intermediateConfig.setIterationId(ITERATION_ID);

    intermediateConfig.setDriver(CollectorMapDriver.class);
    intermediateConfig.setDriverStrategy(DriverStrategy.COLLECTOR_MAP);
    intermediateConfig.addInputToGroup(0);
    intermediateConfig.setInputSerializer(inputSerializer, 0);

    intermediateConfig.setOutputSerializer(outputSerializer);
    intermediateConfig.addOutputShipStrategy(ShipStrategyType.PARTITION_HASH);
    intermediateConfig.setOutputComparator(outputComparator, 0);

    intermediateConfig.setBroadcastInputName("centers", 0);
    intermediateConfig.addBroadcastInputToGroup(0);
    intermediateConfig.setBroadcastInputSerializer(broadcastVarSerializer, 0);

    // the udf
    intermediateConfig.setStubWrapper(
        new UserCodeObjectWrapper<SelectNearestCenter>(new SelectNearestCenter()));

    return mapper;
  }