HTTP Error 400 "Required request part 'file' is not present" when uploading file

Question

I'm trying to make an upload utility to load an excel file and make a bulk insert into DB.

I'm using AngularJS and Spring.

I've been trying for days, but I can't get java to read the uploaded file.

I'm using ngFileUpload and javascript is getting my file, but when I call my Controller the param is null or whatever the http error is the 400 "Required request part 'file' is not present".

Request header

I tried everything, adding the multipartresolver into config; enabling the multipart encoding into application.properties; adding the library into the pom.xml, but it still doesn't works.

server.port=8081
spring.http.encoding.charset=UTF-8
spring.http.encoding.enabled=true
spring.http.multipart.max-file-size=15000000
spring.http.multipart.max-request-size=15000000

---

@Bean
public MultipartResolver multipartResolver() {
     return new CommonsMultipartResolver();
}


@PostMapping(value = "/excelUploader", consumes = "multipart/form-data")
public ResponseEntity<?> saveEnvironmentConfig(@RequestParam("file") MultipartFile submissions){
    return null;
}

EDIT Client Side Part

 $scope.upload = function() {

                    Upload.upload({
                        url: $scope.uploadServiceUrl,
                        data: { file: $scope.files,
                            method: 'POST'}



                    }).then(function(resp) {

                        if ($scope.uploadCompleteFn) {
                            $scope.uploadCompleteFn();
                        }

                        console.log('Upload complete.');

                    }, function(resp) {
                        console.log('Error status: ' + resp.status);
                    });
                };