code: public OutSegment openWriterGc(long sequence)
    {
      int segmentSize = _segmentSizeGc;
      
      SegmentKelp segment = _segmentService.createSegment(segmentSize, getTableKey(), sequence);
      
      addTableSegmentLength(segmentSize);
      
      return new OutSegment(_table, _table.getTableService(), this, segment);
    }
docs: Opens a new segment writer with a specified sequence. Called by the GC
  which has multiple segments with the same sequence number.
  
  @param sequence the sequence id for the new segment.