@SuppressWarnings("unchecked")
    @Override
    public Response process(Request request, Execution execution) {
        DataList dataList = ArrayDataList.createAsync(request); // Default implementation
        incomingData=dataList.incoming();
        return new Response(dataList);
    }
A data producer which producer data which will receive asynchronously.
This is not a realistic, thread safe implementation as only the incoming data
from the last created incoming data can be completed.
container-core/src/test/java/com/yahoo/processing/test/documentation/AsyncDataProducer.java