Angularjs 1.5 file upload

Question

I am using Angularjs 1.5, and trying to upload multiple files but in http request unable to send file data to java service, file data going as empty object.

I am using the following directory to upload the multiple files:

myForm.directive('ngFileModel', ['$parse', function ($parse) {
    return {
        restrict: 'A',
        link: function (scope, element, attrs) {
            var model = $parse(attrs.ngFileModel);
            var isMultiple = attrs.multiple;
            var modelSetter = model.assign;
            element.bind('change', function () {
                var values = [];
                angular.forEach(element[0].files, function (item) {
                    var value = {                       
                        name: item.name,                       
                        size: item.size,                       
                        url: URL.createObjectURL(item),
                        // File Input Value 
                        _file: item
                    };
                    values.push(value);
                });
                scope.$apply(function () {
                    if (isMultiple) {
                        modelSetter(scope, values);
                    } else {
                        modelSetter(scope, values[0]);
                    }
                });
            });
        }
    };
}]);

On http request _file object going as empty object. 1. How can I send file data in _file object?

Query String Parameters:

param: { "files": [{"name":"arrowred.png","size":34516,"url":"blob:http://localhost:7001/24c4d435-3cab-410e-9bf4-8bdce7990f4d","_file":{}}]}