cannot able to send files with extact format in flutter - flutter

Question

I'm currently working in a flutter, I'm trying to send a file to the backend server. But I can send a file but the extension is showing as BIN and the file is not supported.
pick() async {
var img = await ImagePicker().getImage(source: ImageSource.gallery);
image = img;
}
send() async {
// if (imageFile == null) {
// return Get.snackbar("alert", 'Please select image');
// }
try {
String? message = messageController.text;
final url = Uri.parse('http://localhost:8000/integration-test');
//Map<String, String> headers = {'Authorization': 'Bearer $token'};
Uint8List data = await this.image.readAsBytes();
List<int> list = data.cast();
var request = http.MultipartRequest('POST', url)
//..headers.addAll(headers)
..fields['sender'] = "venkat"
..fields['numbers'] = numbers
..fields['message'] = message;
if (image != null) {
request.files.add(http.MultipartFile.fromBytes('file', list,
filename: 'example.jpeg'));
}
var response = await request.send();
//var decoded = await response.stream.bytesToString().then(json.decode);
if (response.statusCode == 200) {
Get.snackbar("alert", 'SUCESS');
} else {
Get.snackbar("alert", 'FAILED');
}
} catch (e) {
Get.snackbar('alert', 'Image failed: $e');
}
}
and help to set the file name dynamically.
when i done it with ajax and jquery it works file i need the exact result like this
let formData = new FormData();
let file = $('#1file')[0].files[0];
const sender=c;
const message = $('.i-message').val();
const datepick=$("#i-datetimepicker").val();
formData.append('sender',c);
formData.append('numbers',JSON.stringify(irecepient));
formData.append('message',message);
if(file){
formData.append('file',file);
}
if(datepick){
formData.append('date',datepick);
}
$.ajax({
type: "POST",
url: "http://localhost:8000/integration-test",
//enctype: 'multipart/form-data',
contentType:false,
processData:false,
data: formData,
success: function (data) {
if(data !=0){
$('.logs').append($('<li>').text("task processing"));
}else{
$('.logs').append($('<li>').text("task failed"));
}
}
});
});
this works good and i expect the above flutter code to do this