code: private TaskAttemptID maskAttemptID(TaskAttemptID attemptId) {
      JobID jobId = new JobID();
      TaskID taskId = attemptId.getTaskID();
      return new TaskAttemptID(jobId.getJtIdentifier(), jobId.getId(),
          attemptId.isMap(), taskId.getId(), attemptId.getId());
    }
docs: Mask the job ID part in a {@link TaskAttemptID}.
  
  @param attemptId
  raw {@link TaskAttemptID} read from trace
  @return masked {@link TaskAttemptID} with empty {@link JobID}.