Class required a bean of type 'java.lang.String' that could not be found

I try to a mailservice in Spring. I use Spring-Boot version 2.1.7.Release and amazon-sqs-java-messaging-lib version 1.0.8.

My code looks like:

    @Service
@RequiredArgsConstructor
public class MailService {

private static final Logger logger = Logger.getLogger(MailService.class.getName());
private final AmazonSQS amazonSQS;

@Value("${aws.sqs.queue.mail}")
private final String sqsQueueMail;

public void sendMail(final SQSMailParams mailParams) {

    final String queueUrl = amazonSQS.getQueueUrl(sqsQueueMail).getQueueUrl();

    try {
        final String messageBody = SQSMailParams.createSQSMailParams(mailParams, mailParams.getTemplateKey(), mailParams.getProcessId()).toJson();
        final SendMessageRequest sendMessageRequest = new SendMessageRequest(queueUrl, messageBody);
        sendMessageRequest.setMessageGroupId("TOLL-BOX-MAIL");

        amazonSQS.sendMessage(sendMessageRequest);
        logger.info("TOLL-BOX mail added to mail queue");
    } catch (JsonProcessingException e) {
        logger.error("Mail cannot be added to the mail queue: " + String.join(",", mailParams.recipients) + "." + e);
    }

    }
}

But i get the following failure by running the code.

2020-03-02 07:34:00.242 ERROR 10568 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 1 of constructor in de.svg.tollbox.service.MailService required a bean of type 'java.lang.String' that could not be found.


Action:

Consider defining a bean of type 'java.lang.String' in your configuration.

Disconnected from the target VM, address: '127.0.0.1:43565', transport: 'socket'

Process finished with exit code 1

Could someone tell me what im doing wrong thank you.

Remove final from sqsQueueMail.

@Value("${aws.sqs.queue.mail}")
private String sqsQueueMail;

That should fix your issue. Somehow, with @RequiredArgsConstructor, the @Value annotation for the variable is not resolved which made the application to look for a bean of type String