JAVA: Hashmap not changing values after writing through socket twice

Question

This application supposed to send and recieve custom type objects that implements interface ContextObject

This object contains the hashmap changes (the problem) , whenever i change it after first .write it doesnt get changed at all.

Server :

      TestingSession(Socket socket) throws Exception {

            try {
                ObjectOutputStream objectOutputStream = new ObjectOutputStream(socket.getOutputStream());
                ObjectInputStream objectInputStream = new ObjectInputStream(socket.getInputStream());
    
                this.socket = socket;
    
                while (!socket.isClosed()) {
                    // reads an object of Type contextObject 
                    ContextObject receivedCO =(ContextObject)  objectInputStream.readObject(); 
    


                     // if its of type UpdateContextObject , then it contains a "changes" hashmap, print it. 
                    if(receivedCO instanceof  UpdateContextObject) {
                        UpdateContextObject ob= (UpdateContextObject) receivedCO;
                        Map<String, String> map = ob.getChanges();
                        for (Map.Entry entry : map.entrySet())
                            logger.trace(entry.getKey() + "  " + entry.getValue());
                    }



                        // send back the results, (not important in this question.)   
                    List queryResult = Query.processQuery(receivedCO);
                    objectOutputStream.writeObject(queryResult);

                }

Client :

            Socket socket;
            socket = new Socket("127.0.0.1", 5050);

            ObjectInputStream objectInputStream = new 
            ObjectInputStream(socket.getInputStream());
            ObjectOutputStream objectOutputStream = new 
            ObjectOutputStream(socket.getOutputStream());


            UpdateContextObject updateCO = new UpdateContextObject();


            // not important, for later processing.
            updateCO.setTable("users");
            updateCO.setAttributes(new HashMap<>());


             // This map that doesnt get changed.
            Map<String,String> changes = new HashMap<>();
            changes.put("Id","1");
            updateCO.setChanges(changes);


            int i=0;
            while(true){
                i++;

                changes.put("Id",""+i);


                objectOutputStream.writeObject(updateCO);
                objectInputStream.readObject();

                changes.put("username","3");
                System.out.println(changes.get("Id"));
                if(i>50) break;
            }

Server output :

setting Id to 1

setting Id to 1

setting Id to 1

setting Id to 1

setting Id to 1

Client output:

1 2 3 4 5 ..