code: public PlainChangesLog read(ObjectReader in) throws UnknownClassIdException, IOException
     {
        int key;
        if ((key = in.readInt()) != SerializationConstants.PLAIN_CHANGES_LOG_IMPL)
        {
           throw new UnknownClassIdException("There is unexpected class [" + key + "]");
        }
        int eventType = in.readInt();
  
        String sessionId = in.readString();
  
        List<ItemState> items = new ArrayList<ItemState>();
        int listSize = in.readInt();
        for (int i = 0; i < listSize; i++)
        {
           ItemStateReader isr = new ItemStateReader(holder, spoolConfig);
           ItemState is = isr.read(in);
           items.add(is);
        }
  
        return new PlainChangesLogImpl(items, sessionId, eventType);
     }
docs: Read and set PlainChangesLog data.
  
  @param in
  ObjectReader.
  @return PlainChangesLog object.
  @throws UnknownClassIdException
  If read Class ID is not expected or do not exist.
  @throws IOException
  If an I/O error has occurred.