@Override
    @SuppressWarnings("unchecked")
    public void translateNode(
        Combine.PerKey<K, InputT, OutputT> transform, FlinkBatchTranslationContext context) {
      DataSet<WindowedValue<KV<K, InputT>>> inputDataSet =
          context.getInputDataSet(context.getInput(transform));

      CombineFnBase.PerKeyCombineFn<K, InputT, AccumT, OutputT> combineFn =
          (CombineFnBase.PerKeyCombineFn<K, InputT, AccumT, OutputT>) transform.getFn();

      KvCoder<K, InputT> inputCoder = (KvCoder<K, InputT>) context.getInput(transform).getCoder();

      Coder<AccumT> accumulatorCoder;

      try {
        accumulatorCoder =
            combineFn.getAccumulatorCoder(
                context.getInput(transform).getPipeline().getCoderRegistry(),
                inputCoder.getKeyCoder(),
                inputCoder.getValueCoder());
      } catch (CannotProvideCoderException e) {
        throw new RuntimeException(e);
      }

      WindowingStrategy<?, ?> windowingStrategy =
          context.getInput(transform).getWindowingStrategy();

      TypeInformation<WindowedValue<KV<K, AccumT>>> partialReduceTypeInfo =
          context.getTypeInfo(
              KvCoder.of(inputCoder.getKeyCoder(), accumulatorCoder), windowingStrategy);

      Grouping<WindowedValue<KV<K, InputT>>> inputGrouping =
          inputDataSet.groupBy(new KvKeySelector<InputT, K>(inputCoder.getKeyCoder()));

      // construct a map from side input to WindowingStrategy so that
      // the OldDoFn runner can map main-input windows to side input windows
      Map<PCollectionView<?>, WindowingStrategy<?, ?>> sideInputStrategies = new HashMap<>();
      for (PCollectionView<?> sideInput : transform.getSideInputs()) {
        sideInputStrategies.put(sideInput, sideInput.getWindowingStrategyInternal());
      }

      if (windowingStrategy.getWindowFn().isNonMerging()) {
        WindowingStrategy<?, BoundedWindow> boundedStrategy =
            (WindowingStrategy<?, BoundedWindow>) windowingStrategy;

        FlinkPartialReduceFunction<K, InputT, AccumT, ?> partialReduceFunction =
            new FlinkPartialReduceFunction<>(
                combineFn, boundedStrategy, sideInputStrategies, context.getPipelineOptions());

        FlinkReduceFunction<K, AccumT, OutputT, ?> reduceFunction =
            new FlinkReduceFunction<>(
                combineFn, boundedStrategy, sideInputStrategies, context.getPipelineOptions());

        // Partially GroupReduce the values into the intermediate format AccumT (combine)
        GroupCombineOperator<WindowedValue<KV<K, InputT>>, WindowedValue<KV<K, AccumT>>>
            groupCombine =
                new GroupCombineOperator<>(
                    inputGrouping,
                    partialReduceTypeInfo,
                    partialReduceFunction,
                    "GroupCombine: " + transform.getName());

        transformSideInputs(transform.getSideInputs(), groupCombine, context);

        TypeInformation<WindowedValue<KV<K, OutputT>>> reduceTypeInfo =
            context.getTypeInfo(context.getOutput(transform));

        Grouping<WindowedValue<KV<K, AccumT>>> intermediateGrouping =
            groupCombine.groupBy(new KvKeySelector<AccumT, K>(inputCoder.getKeyCoder()));

        // Fully reduce the values and create output format OutputT
        GroupReduceOperator<WindowedValue<KV<K, AccumT>>, WindowedValue<KV<K, OutputT>>>
            outputDataSet =
                new GroupReduceOperator<>(
                    intermediateGrouping, reduceTypeInfo, reduceFunction, transform.getName());

        transformSideInputs(transform.getSideInputs(), outputDataSet, context);

        context.setOutputDataSet(context.getOutput(transform), outputDataSet);

      } else {
        if (!windowingStrategy.getWindowFn().windowCoder().equals(IntervalWindow.getCoder())) {
          throw new UnsupportedOperationException(
              "Merging WindowFn with windows other than IntervalWindow are not supported.");
        }

        // for merging windows we can't to a pre-shuffle combine step since
        // elements would not be in their correct windows for side-input access

        WindowingStrategy<?, IntervalWindow> intervalStrategy =
            (WindowingStrategy<?, IntervalWindow>) windowingStrategy;

        FlinkMergingNonShuffleReduceFunction<K, InputT, AccumT, OutputT, ?> reduceFunction =
            new FlinkMergingNonShuffleReduceFunction<>(
                combineFn, intervalStrategy, sideInputStrategies, context.getPipelineOptions());

        TypeInformation<WindowedValue<KV<K, OutputT>>> reduceTypeInfo =
            context.getTypeInfo(context.getOutput(transform));

        Grouping<WindowedValue<KV<K, InputT>>> grouping =
            inputDataSet.groupBy(new KvKeySelector<InputT, K>(inputCoder.getKeyCoder()));

        // Fully reduce the values and create output format OutputT
        GroupReduceOperator<WindowedValue<KV<K, InputT>>, WindowedValue<KV<K, OutputT>>>
            outputDataSet =
                new GroupReduceOperator<>(
                    grouping, reduceTypeInfo, reduceFunction, transform.getName());

        transformSideInputs(transform.getSideInputs(), outputDataSet, context);

        context.setOutputDataSet(context.getOutput(transform), outputDataSet);
      }
    }
    @Override
    public void translateNode(
        GroupByKey<K, InputT> transform, FlinkBatchTranslationContext context) {

      // for now, this is copied from the Combine.PerKey translater. Once we have the new runner API
      // we can replace GroupByKey by a Combine.PerKey with the Concatenate CombineFn

      DataSet<WindowedValue<KV<K, InputT>>> inputDataSet =
          context.getInputDataSet(context.getInput(transform));

      Combine.KeyedCombineFn<K, InputT, List<InputT>, List<InputT>> combineFn =
          new Concatenate<InputT>().asKeyedFn();

      KvCoder<K, InputT> inputCoder = (KvCoder<K, InputT>) context.getInput(transform).getCoder();

      Coder<List<InputT>> accumulatorCoder;

      try {
        accumulatorCoder =
            combineFn.getAccumulatorCoder(
                context.getInput(transform).getPipeline().getCoderRegistry(),
                inputCoder.getKeyCoder(),
                inputCoder.getValueCoder());
      } catch (CannotProvideCoderException e) {
        throw new RuntimeException(e);
      }

      WindowingStrategy<?, ?> windowingStrategy =
          context.getInput(transform).getWindowingStrategy();

      TypeInformation<WindowedValue<KV<K, List<InputT>>>> partialReduceTypeInfo =
          new CoderTypeInformation<>(
              WindowedValue.getFullCoder(
                  KvCoder.of(inputCoder.getKeyCoder(), accumulatorCoder),
                  windowingStrategy.getWindowFn().windowCoder()));

      Grouping<WindowedValue<KV<K, InputT>>> inputGrouping =
          inputDataSet.groupBy(new KvKeySelector<InputT, K>(inputCoder.getKeyCoder()));

      FlinkPartialReduceFunction<K, InputT, List<InputT>, ?> partialReduceFunction;
      FlinkReduceFunction<K, List<InputT>, List<InputT>, ?> reduceFunction;

      if (windowingStrategy.getWindowFn().isNonMerging()) {
        @SuppressWarnings("unchecked")
        WindowingStrategy<?, BoundedWindow> boundedStrategy =
            (WindowingStrategy<?, BoundedWindow>) windowingStrategy;

        partialReduceFunction =
            new FlinkPartialReduceFunction<>(
                combineFn,
                boundedStrategy,
                Collections.<PCollectionView<?>, WindowingStrategy<?, ?>>emptyMap(),
                context.getPipelineOptions());

        reduceFunction =
            new FlinkReduceFunction<>(
                combineFn,
                boundedStrategy,
                Collections.<PCollectionView<?>, WindowingStrategy<?, ?>>emptyMap(),
                context.getPipelineOptions());

      } else {
        if (!windowingStrategy.getWindowFn().windowCoder().equals(IntervalWindow.getCoder())) {
          throw new UnsupportedOperationException(
              "Merging WindowFn with windows other than IntervalWindow are not supported.");
        }

        @SuppressWarnings("unchecked")
        WindowingStrategy<?, IntervalWindow> intervalStrategy =
            (WindowingStrategy<?, IntervalWindow>) windowingStrategy;

        partialReduceFunction =
            new FlinkMergingPartialReduceFunction<>(
                combineFn,
                intervalStrategy,
                Collections.<PCollectionView<?>, WindowingStrategy<?, ?>>emptyMap(),
                context.getPipelineOptions());

        reduceFunction =
            new FlinkMergingReduceFunction<>(
                combineFn,
                intervalStrategy,
                Collections.<PCollectionView<?>, WindowingStrategy<?, ?>>emptyMap(),
                context.getPipelineOptions());
      }

      // Partially GroupReduce the values into the intermediate format AccumT (combine)
      GroupCombineOperator<WindowedValue<KV<K, InputT>>, WindowedValue<KV<K, List<InputT>>>>
          groupCombine =
              new GroupCombineOperator<>(
                  inputGrouping,
                  partialReduceTypeInfo,
                  partialReduceFunction,
                  "GroupCombine: " + transform.getName());

      Grouping<WindowedValue<KV<K, List<InputT>>>> intermediateGrouping =
          groupCombine.groupBy(new KvKeySelector<List<InputT>, K>(inputCoder.getKeyCoder()));

      // Fully reduce the values and create output format VO
      GroupReduceOperator<WindowedValue<KV<K, List<InputT>>>, WindowedValue<KV<K, List<InputT>>>>
          outputDataSet =
              new GroupReduceOperator<>(
                  intermediateGrouping, partialReduceTypeInfo, reduceFunction, transform.getName());

      context.setOutputDataSet(context.getOutput(transform), outputDataSet);
    }