Angular Spring Boot (File+FormData) Upload + Object

Question

My api return error 403 when i try to send a file + object from angular. once i remove the object from angular ts and also from my backend api then i send only the file it works. i think i have a problem in the way i send formData. the car is my object that contains name and desscription.

I'm using angular 17

TS

addCar(carForm: NgForm) {
    const carFormData = this.prepareFormDate(this.car);
    this.carService.addCar(carFormData).subscribe(
      (response: Car) => {
        console.log(response);
        carForm.reset();
      },
      (error: HttpErrorResponse) => {
        console.log(error);
      }
    );
  }

  prepareFormDate(car: Car): FormData {
    const formData = new FormData();
    formData.append(
      'car',
      new Blob([JSON.stringify(car)], {type: 'application/json'})
    );

    for(var i=0; i < car.carImages.length; i++) {
      formData.append(
        'imageFile',
        car.carImages[i].file,
        car.carImages[i].file.name
      );
    }

    return formData;
  }
  onFileSelected(event: any) {
    if(event.target.files) {
      const file = event.target.files[0];

      const fileHandle: FileHandle = {
        file: file,
        url: this.sanitizer.bypassSecurityTrustUrl(
          window.URL.createObjectURL(file)
        )
      }

      this.car.carImages.push(fileHandle);
    }
  }
}

My service :

public addCar(car: FormData) {
    return this.httpClient.post<Car>(`${API_URL}/car/addCar`, car);
  }

Spring boot

@PostMapping(value = "/addCar", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public ResponseEntity<CarEntity> addNewCar(@RequestPart("car") CarEntity car,
                                               @RequestPart("imageFile") MultipartFile[] file) throws IOException {
        log.info("[addNewCar]");
            Set<ImageEntity> images = carService.uploadImages(file);
            car.setCarImages(images);
            CarEntity carEntity = carService.addNewCar(car);
            return ResponseEntity.status(HttpStatus.OK).body(carEntity);
    }

is there a probleme with the data i send from angular ?