The problem my feature request is related to:

I am using the standard VS-Code setup to develop a flutter app.

Recently I needed imports of the form:
import 'package:highlight/languages/java.dart';

So not like:
import 'package:<package_name>/<file_name>.dart';

But like:
import 'package:<package_name>/<folder_name>/<file_name>.dart';

I tried to go about it the usual way, simply using this suggestion to automatically import, but it failed:

Firstly, if you just start with such an import in an empty project, you sometimes don't even get that option:

(Perhaps even with any import?)

Tough, after a few seconds, things normalize regarding that:

So that's not that much of a problem in my opinion.

Now for the real "issue", if you just try the "auto-import" suggestion, you get:

[flutter_application_1] flutter pub add highlight/languages
Using a naked argument for directory is deprecated and will stop working in a future Flutter release.

Use --directory instead.
Expected to find project root in highlight/languages.
exit code 1

If you modify the import to look like this, however:
import 'package:highlight/sth.dart';
(With some nonexistent file name)

Then the import works as expected, and you can change the import back to:
import 'package:highlight/languages/java.dart';
which then works.

It seems to me, the layman, that importing only part of a library is not possible (anymore?) for some reason, causing the "auto-import" to needlessly fail, when it could instead just try to import the whole library, not just the specific folder.

The "easy" solution:

From my layman perspective, it seems like a simple solution would be for the auto-importer to simply always import the whole library.

Possible issues with the "easy" solution:

As I'm not that experienced with dart and flutter, it may be that in other use cases, people actually need the auto-import to work this way, and I simply don't know it. In this case, it would probably be best to have auto-import first try to work as it does now, and then have it work as in the "easy" solution if and only if the other way does not work.