code: public void writeExternal(ObjectOutput out) throws IOException
     {
        // write -1 if systemId == null
        // write 1 if systemId != null
  
        if (systemId != null)
        {
           out.writeInt(1);
  
           byte[] buff = systemId.getBytes(Constants.DEFAULT_ENCODING);
           out.writeInt(buff.length);
           out.write(buff);
        }
        else
        {
           out.writeInt(-1);
        }
  
        int listSize = changesLogs.size();
        out.writeInt(listSize);
        for (int i = 0; i < listSize; i++)
        {
           out.writeObject(changesLogs.get(i));
        }
     }
docs: {@inheritDoc}