Composer package breaks project when using recommended app()->langPath() method

[halloei]

• Lumen Version: 8.3.4
• Laravel Version: 8.83.1
• PHP Version: 8.1.2
• Database Driver & Version: %

Description:

I did not yet upgrade my Laravel and Lumen projects to version 9, but I did prepare my Laravel and Lumen packages for it.
The upgrade guide recommends to set the path for package language files with app()->langPath() instead of hard-coding it. I changed that and did now a simple composer update in my Lumen project (still version 8) and it broke, because its Application class does not contain a langPath() method. I'm surprised version 9 of the framework doesn't either.

Steps To Reproduce:

In your Lumen project, pull in a Laravel/Lumen package with the following service provider:

class MyPackageServiceProvider extends ServiceProvider
{
    public function boot(): void
    {
        $this->publishes([__DIR__ . '/../lang' => $this->app->langPath() . "/vendor/my-package"]);
    }
}

[driesvints]

It's getLanguagePath in Lumen:

lumen-framework/src/Application.php

Line 605 in 1b05a57

protected function getLanguagePath()

[halloei]

I noticed that. But it's not possible to call that method since it's protected. However, if it was public, should we add a switch to our package's service provider that checks for Laravel (use langPath()) or Lumen (use getLanguagePath())? Seems odd to me.

[driesvints]

@halloei you can send in a PR for a langPath method if you want. I didn't see the method was protected.