How to change default language in Middleware

[ducvu91]

Hello,
I meet issue with default language. My site is multi tenant, each tenant has default language different. But now, i only set default language on provider, how i can set it in Middleware?.
My Case is:
my app have config default locale "en", with japan tenant, it default have ja, but when i set Config::set('app.locale', $lang); thì it not apply on Middleware. when i access domain/ja it still there, but when access domain/en it redirect to domain. it wrong beacause the lang default is ja, not en
but when i set in AppServiceProvider, it apply.
i don't know why, and i can't move logic detect tenant in to AppServiceProvider.
Pls help

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UPDATE:
i seen in code have function
public function getDefaultLocale()
{
return $this->defaultLocale;
}

$this->defaultLocale = $this->configRepository->get('app.locale');

can you add function setDefaultLocale() ?