deserialised = true;
   public void readExternal(ObjectInput in) throws IOException   {      try      {         super.readExternal(in);         content = (ArrayList) in.readObject();         position = in.readInt();         offset = in.readInt();         size = in.readInt();         deserialised = true;      }      catch (ClassNotFoundException e)      {         log.error("Failed to find class", e);         throw new IOException(e.getMessage());      }   }