code: private void fillHeader()
    {
      byte[] buffer = _indexBuffer;
      
      Arrays.fill(buffer, (byte) 0x0);
      
      int index = 0;
      
      BitsUtil.writeLong(buffer, index, _segment.getSequence());
      index += 8;
      
      byte []tableKey = _table.tableKey();
      System.arraycopy(tableKey, 0, buffer, index, tableKey.length);
      index += tableKey.length;
  
      /*
      BitsUtil.writeInt16(buffer, index, tail);
      index += 2;
    
      buffer[index] = (byte) (isCont ? 1 : 0);
      index++;
      */
      
      _indexTail = index;
      
      fillFooter(buffer, FOOTER_OFFSET, index, false);
    }
docs: <pre>
  u64 sequence
  b32 key
  </pre>