How to set content type on MultipartFile by looking up mime type?

[Yogesh070]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:
I have defined the api as:

@post('')
Future saveProfileGreetings(
@part() File file,
@part() String link,
@SendProgress() ProgressCallback onSendProgress,
);

This works fine but I want to assign content type on MultipartFile by looking up mime type.

Expected behavior
I want to generate the api as the following where i can set content type as :

contentType: MediaType.parse(lookupMimeType(file.path)!),

@OverRide
Future saveProfileGreetings(
File file,
String link,
void Function(int, int) onSendProgress,
) async {
final _extra = <String, dynamic>{};
final queryParameters = <String, dynamic>{};
final _headers = <String, dynamic>{};
final _data = FormData();
_data.files.add(MapEntry(
'file',
MultipartFile.fromFileSync(
file.path,
filename: file.path.split(Platform.pathSeparator).last,
contentType: MediaType.parse(lookupMimeType(file.path)!),
),
));
_data.fields.add(MapEntry(
'link',
link,
));
await _dio.fetch(_setStreamType(Options(
method: 'POST',
headers: _headers,
extra: _extra,
contentType: 'multipart/form-data',
)
.compose(
_dio.options,
'',
queryParameters: queryParameters,
data: _data,
onSendProgress: onSendProgress,
)
.copyWith(
baseUrl: _combineBaseUrls(
_dio.options.baseUrl,
baseUrl,
))));
}

Additional context
Add any other context about the problem here.