What is your question?

1. I create a class and wanted to use "Share.shareXFiles".
2. I add "import 'package:share_plus/share_plus.dart';"
3. When writting this line : await Share.shareXFiles([XFile(filename)], I have this message : The method 'XFile' isn't defined for the type 'DataShareService'.
4. So I have to add this import "import 'package:cross_file/cross_file.dart';"
5. But now I have this message "package:cross_file/cross_file.dart Depend on referenced packages.dartdepend_on_referenced_packages"

In your example, you don't have the problem because XFile is referenced by this import : 'package:image_picker/image_picker.dart'

In the example below, I have commented the line of the import 'package:cross_file/cross_file.dart' so you can see the problem. If you uncomment the import 'package:cross_file/cross_file.dart'; you'll see the other message.
Thanks.

Code sample :

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:share_plus/share_plus.dart';
// TODO : uncomment the line below to refrence XFile
//import 'package:cross_file/cross_file.dart';

class DataShareService {
void sharingFile({
required String filename,
required BuildContext context,
required String subject,
}) async {

final box = context.findRenderObject() as RenderBox?;

await Share.shareXFiles([XFile(filename)],
    subject: subject,
    sharePositionOrigin: box!.localToGlobal(Offset.zero) & box.size);

}
}

Checklist before submitting a question

• I Google'd a solution and I couldn't find it
• I searched on StackOverflow for a solution and I couldn't find it
• I read the README.md file of the plugin
• I am using the latest version of the plugin
• All dependencies are up to date with flutter pub upgrade
• I did a flutter clean
• I tried running the example project