Loss of messages in RabbitMQ

I am trying to create a persistent message queue with some delay per message. In Java code, it looks like this:

    ConnectionFactory factory = new ConnectionFactory();
    factory.setHost("localhost");
    Connection connection = factory.newConnection();
    Channel channel = connection.createChannel();

    channel.exchangeDeclare("WorkExchange", "direct");
    channel.queueDeclare("WorkQueue", true, false, false, null);
    channel.queueBind("WorkQueue", "WorkExchange", "");

    Map<String, Object> args = new HashMap<>();
    args.put("x-dead-letter-exchange", "WorkExchange");

    channel.exchangeDeclare("RetryExchange", "direct");
    channel.queueDeclare("RetryQueue", true, false, false, args);
    channel.queueBind("RetryQueue", "RetryExchange", "");

    channel.confirmSelect();
    BasicProperties properties = new BasicProperties();
    properties.setDeliveryMode(2);
    properties.setExpiration("120000");
    channel.basicPublish("RetryExchange", "", properties, "Hello world!".getBytes());
    channel.waitForConfirmsOrDie();
    connection.close();

      

        
        
        
      

    

However, I have some persistence issues. When I stop the server wait for a while and start again, the messages that should go to the WorkQueue will just disappear. What am I doing wrong? Or is it by design?