public class OwnerProfileUpdateDTO {

    private String firstName;

    private String lastName;

    private String phone;

    private String company;

    private long countryId;
    private long regionId;
    private long townId;

    private MultipartFile avatar;

    public OwnerProfileUpdateDTO() {}

    // getters and setters

}

@RestController
@Secured("OWNER")
@PreAuthorize("isAuthenticated()")
@RequestMapping(value = "/api/v1/owner",produces = MediaType.APPLICATION_JSON_VALUE)
public class ApiOwnerController {

    @Autowired
    private OwnerService ownerService;

    private static final Logger LOGGER = LogManager.getLogger(ApiOwnerController.class);

    @PostMapping(value = "/profile/update", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public Response fillUpdate(Response response, OwnerProfileUpdateDTO ownerProfileUpdateDTO) {
        LOGGER.info(ownerProfileUpdateDTO);
        response.setSuccess("OK");
        return response;
    }

}

$.ajax({
       url: 'update',
       data: new FormData($('form')[0]),
       type: 'POST',
       dataType: 'json',
       processData: false,
       contentType: false,
       enctype: 'multipart/form-data'
})

org.springframework.web.HttpMediaTypeNotSupportedException: Content type 'multipart/form-data;boundary=----WebKitFormBoundary0iIfmbRKA2DP0lnF;charset=UTF-8' not supported

<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>

@Bean(name = "multipartResolver")
public CommonsMultipartResolver multipartResolver() {
    CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
    multipartResolver.setMaxUploadSize(100000);
    return multipartResolver;
}

@PostMapping(value = "/profile/update", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public Response fillUpdate(Response response, @ModelAttribute 
 OwnerProfileUpdateDTO ownerProfileUpdateDTO) {
        LOGGER.info(ownerProfileUpdateDTO);
        response.setSuccess("OK");
        return response;
    }