Multipart "filename" from browser

[remalkoil]

Hello,
I've the following api service's method:

@POST('/my-custom-url')
@Multipart
async uploadFileFromBrowser(@Part('file') file: PartDescriptor<File>): Promise<Response<any>> {
   return {} as Response;
}

I'm calling it (from an Angular project) with the following code:

async uploadAction() {
  const fileInput = document.getElementById('file') as HTMLInputElement;
  const files = fileInput.files;
  const file = files[0];
  const response = await this.api.uploadFileFromBrowser({value: file, filename: file.name});
}

When I call the uploadAction method the "filename field" is the string: "[object Object]" instead of the "textual name of file".

------WebKitFormBoundaryWY9IohJDLcjoMBw7
Content-Disposition: form-data; name="file"; filename="[object Object]"
Content-Type: image/png
[...]

Inside dataResolver.ts, method resolve(headers: any, data: any) the line n. 44 is:
formData.append(key, data[key].value, { filename: data[key].filename });
maybe should be:
formData.append(key, data[key].value, data[key].filename);

Best regards,
Daniele