public ReduceTaskImpl(jobId JobId, partition int, eventHandler EventHandler, jobFile Path, conf JobConf, numMapTasks int, taskAttemptListener TaskAttemptListener, committer OutputCommitter, jobToken Token<JobTokenIdentifier>, credentials Credentials, clock Clock, completedTasksFromPreviousRun Map<TaskId,TaskInfo>, startCount int, metrics MRAppMetrics, appContext AppContext)