400 issue with spring boot after trying to fix CORS issue

Question

I'm getting a 400 bad request issue after I tried to fix the CORS issue as below with spring boot

nested exception is com.fasterxml.jackson.core.JsonParseException Unrecognized token 'assessmentLevel': was expecting ('true', 'false' or 'null')\n at [Source: (PushbackInputStream); line: 1, column: 17]","path":"/assessments/createAssessment"}

CorsFilter:

public class CorsFilter extends GenericFilterBean implements Filter {

       @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            HttpServletResponse response = (HttpServletResponse) servletResponse;
            response.setHeader("Access-Control-Allow-Origin", "*");
            response.setHeader("Access-Control-Allow-Methods", "*");
            response.setHeader("Access-Control-Allow-Headers", "*");
            response.setHeader("Access-Control-Allow-Credentials", "false");
            response.setHeader("Access-Control-Max-Age", "3600");
            filterChain.doFilter(servletRequest, servletResponse);
        }

    }

Controler:

@RequestMapping(method = RequestMethod.POST, path ="createAssessment")
@ResponseBody
public String createAssessment(@RequestBody AssessmentRequest assessmentRequest) {
    return assessmentService.addAssessment(assessmentRequest);
}

Filter Config:

@Bean
public FilterRegistrationBean<CorsFilter> corsFilter(){
    FilterRegistrationBean<CorsFilter> registrationBean
            = new FilterRegistrationBean<>();

    registrationBean.setFilter(new CorsFilter());
    registrationBean.addUrlPatterns("/assessments/*");
    registrationBean.setOrder(1);

    return registrationBean;
}

Request Payload for the request:

assessmentLevel=sa&assessmentSubTopic=asd&assessmentTopic=asdf&createdBy=d&rating=1

Request Body:

public class AssessmentRequest {
    private String assessmentTopic;
    private String assessmentSubTopic;
    private String createdBy;
    private String rating;
    private String assessmentLevel;
//Getter and setters
}

AJAX Call

$.ajax({
                url : 'http://localhost:8080/assessments/addAssessment',
                dataType : 'json',
                type : 'POST',
                contentType: "application/json",
                beforeSend : function (xhr) {
                    xhr.setRequestHeader('Accept', '*/*');
                    xhr.setRequestHeader('Content-Type', 'application/json');

                },
                data : {
                    'assessmentTopic' : $('.assessment-topic').val(),
                    'assessmentSubTopic' : $('.assessment-sub-topic').val(),
                    'createdBy' : $('.assessment-creator').val(),
                    'rating' : $('.assessment-rating').val(),
                    'assessmentLevel' : $('.assessment-level').val()
                },
                success : function (response) {
                    assessmentId = response;
                    $('.choose-file').removeClass('hidden');
                    $('.form-control').attr('disabled', true);
                    $('.create-assessment-button').attr('disabled', true);
                },
                error : function (xhr, status, error) {
                    alert('failed');
                }
            });