LoadPipelineStepTask
constructor(batchAccumulator: BatchAccumulator<S, K1, T, U>, inputFlow: Flow<PipelineEvent<K1, T>>, batchUpdateQueue: QueueWriter<BatchUpdate>, outputPartitioner: OutputPartitioner<K1, T, K2, U>?, outputQueue: PartitionedQueue<PipelineEvent<K2, U>>?, flushStrategy: PipelineFlushStrategy?, part: Int, numWorkers: Int, stepId: String, streamCompletions: ConcurrentHashMap<Pair<String, DestinationStream.Descriptor>, AtomicInteger>, maxNumConcurrentKeys: Int? = null)