I configured my RabbitMQ to use the following message converter: Jackson2JsonMessageConverter. However, it created a problem: when the producer sends message as a JSON String, the consumer received this String double-encoded.

Example:

The string sent by producer:     "message": "Hello World!" 
The string received by consumer: ""message": "Hello World!""

What I tried:

One of the solutions is to remove the Jackson2JsonMessageConverter from my RabbitMQ configuration, however I need Jackson2JsonMessageConverter because one of my other producers sends List<List<MyObject>> to the queue, and I want to be able to deserialize it. So, removing Jackson2JsonMessageConverter is not going to be a valid solution for me.

RabbitMQConfig.java:

package dev.abu.screener_backend.rabbitmq;

import org.springframework.amqp.core.AmqpAdmin;
import org.springframework.amqp.rabbit.connection.CachingConnectionFactory;
import org.springframework.amqp.rabbit.core.RabbitAdmin;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class RabbitMQConfig {

    @Bean
    public AmqpAdmin amqpAdmin(CachingConnectionFactory connectionFactory) {
        return new RabbitAdmin(connectionFactory);
    }

    @Bean
    public RabbitTemplate rabbitTemplate(CachingConnectionFactory connectionFactory) {
        RabbitTemplate rabbitTemplate = new RabbitTemplate(connectionFactory);
        rabbitTemplate.setMessageConverter(jacksonConverter());
        return rabbitTemplate;
    }

    @Bean
    public Jackson2JsonMessageConverter jacksonConverter() {
        return new Jackson2JsonMessageConverter();
    }
}

Methods from RabbitMQService.java to create queues, consumers and listeners:

public void createQueue(String queueName) {
        amqpAdmin.declareQueue(new Queue(queueName, false, true, true));
}

public void createConsumer(String queueName) {
        DirectMessageListenerContainer container = new DirectMessageListenerContainer(connectionFactory);
        container.setQueueNames(queueName);
        container.setMessageListener(getListener());
        container.start();
    }

public MessageListener getListener() {
        return (Message message) -> {
            String payload = new String(message.getBody());
            System.out.println(payload); 
            // and doing something here with payload ...
        };
}

And finally, this is how my producers sends a message to a queue:

String data =
        """
        "message": "Hello World!"
        """; // this is example json
rabbitTemplate.convertAndSend(queue, data);

Any help will be appreciated! Thank you so much in advance!