code: public static long getProcessedCount(List<TaskState> taskStates) {
      long value = 0;
  
      for (TaskState taskState : taskStates) {
        value += taskState.getPropAsLong(ConfigurationKeys.WRITER_RECORDS_WRITTEN, 0);
      }
  
      return value;
    }
docs: Get the number of records written by all the writers
  @return Sum of the writer records written count across all tasks