Optimizely / Episerver: Do not use a thread to resolve the current language

Using a thread to resolve the current language in Optimizely is not recommended. If you check the Thread.CurrentThread.CurrentCulture locally, it might yield the specific culture (e.g. en-US), but it might not work as expected in the DXP (Digital Experience Platform) environment.

For the instance, the thread might be invariant and yield the "iv" code instead of the actual culture code. In that case, data you might expect might not be loaded.

The invariant culture is a culture that is culture-independent. It is described as the following:

LCID: 127
KeyboardLayoutId: 127
DisplayName Invariant Language (Invariant Country)
NativeName: Invariant Language (Invariant Country)
TwoLetterISOLanguageName: iv
ThreeLetterISOLanguageName: ivl
ThreeLetterWindowsLanguageName: IVL

Solution? There are many. The most obvious that comes to mind are:

Set a cookie with the language code.
Resolve the language from the URL.
Use the ContentLanguage.PreferredCulture property.
- It uses the IContentLanguageAccessor.Language under the hood which uses the _cache["EPiServer:ContentLanguage"] to store the language.

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