所以我有这个使用Java套接字的类：

public class Connection {
    private final Socket socket;

    private final PrintWriter out;
    private final BufferedReader in;

    private final ObjectOutputStream objectOut;
    private final ObjectInputStream objectIn;

    public Connection(Socket socket) throws IOException {
        this.socket = socket;
        this.out = new PrintWriter(socket.getOutputStream(), true);
        this.in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        this.objectOut = new ObjectOutputStream(socket.getOutputStream());
        this.objectIn = new ObjectInputStream(socket.getInputStream());
    }

    public void close() throws IOException {
        socket.close();
        out.close();
        in.close();
        objectOut.close();
        objectIn.close();
    }
    
    @Override
    public String toString() {
        return socket.getInetAddress() + ":" + socket.getPort();
    }
}

在close方法中，当socket.close（）被调用时，我真正需要关闭的是什么？