public void writeExternal(final ObjectOutput s) throws IOException {
            s.writeInt(hashCode);
            s.writeObject(key);
            s.writeObject(value);
            s.writeObject(next);
        }

        @SuppressWarnings("unchecked")
        @Override
        public void readExternal(final ObjectInput s) throws IOException, ClassNotFoundException {
            hashCode = s.readInt();