code: @Override
    public void beginSlice() {
      log.fine("Beginning slice in shard: " + shardLogQuery.getStartTimeUsec() + "-"
          + shardLogQuery.getEndTimeUsec());
      LogService logService = LogServiceFactory.getLogService();
  
      if (lastOffset != null) {
        shardLogQuery.offset(lastOffset);
      }
      logIterator = logService.fetch(shardLogQuery).iterator();
    }
docs: Prepare this slice for reading. If this the first slice in the shard, then the shardStartTime
  will be used. However if the is not the first slice use the last time read (+1, since that
  timestamp was already read) as the starting point.