Send json with Ajax to RestController of Spring Boot (Content type 'application/json;charset=UTF-8' not supported error)

Question

I have a problem to send JSON data to the method of RestController. I got this kind of error shown below.

error: "Unsupported Media Type"
message: "Content type 'application/json;charset=UTF-8' not supported"

Here is my a related method in js.

function postQuestion() {
    url = contextPath + "post_question/" + productId;
    question = $("#question").val();

    jsonData = {questionContent: question};

    $.ajax({
        type: 'POST',
        url: url,
        beforeSend: function(xhr) {
            xhr.setRequestHeader(csrfHeaderName, csrfValue);
        },
        data: JSON.stringify(jsonData),
        contentType: 'application/json'
    }).done(function(response) {
        $("#modalDialog").on("hide.bs.modal", function(e) {
            $("#question").val(""); 
        });

        .....
    }).fail(function() {
        .....
    });         
}

Here is my method defined in RestController.

@PostMapping(value="/post_question/{productId}")
    public ResponseEntity<?> postQuestion(@RequestBody Question question,
            @PathVariable(name = "productId") Integer productId,
            HttpServletRequest request) throws ProductNotFoundException, IOException {

        LOGGER.info("QuestionRestController | postQuestion is called");
        
        LOGGER.info("QuestionRestController | postQuestion | question : " + question.getQuestionContent());
        LOGGER.info("QuestionRestController | postQuestion | productId : " + productId);
        
        Customer customerUser = authenticationControllerHelperUtil.getAuthenticatedCustomer(request);
        
        LOGGER.info("QuestionRestController | postQuestion | customerUser : " + customerUser.getFullName());
        
        if (customerUser == null) {
            return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
        }

        questionService.saveNewQuestion(question, customerUser, productId);

        return new ResponseEntity<>(HttpStatus.OK);
    }

Here is my Question Entity shown below.

@Entity
@Table(name = "questions")
@Getter
@Setter
public class Question implements Serializable{

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    
    @Column(name = "question")
    private String questionContent;

}

Even if I defined dataType:'json' in js or consumes={"application/json;charset=UTF-8"} in the method of RestController , All these couldn't help me fix my issue.

How can I fix it?