docs: private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException
      {
          // We never write any superflous data to disk so on a read
          // offset is always going to be set to 0.
          _offset = 0;
          _length = in.readInt();
  
          _bytes = new byte[_length];
          in.readFully(_bytes, _offset, _length);
      }