const FTSLanguage& FTSSpec::_getLanguageToUseV1(const BSONObj& userDoc) const {
    BSONElement e = userDoc[_languageOverrideField];
    if (e.type() == String) {
        const char* x = e.valuestrsafe();
        if (strlen(x) > 0) {
            StatusWithFTSLanguage swl = FTSLanguage::make(x, TEXT_INDEX_VERSION_1);
            dassert(swl.isOK());  // make() w/ TEXT_INDEX_VERSION_1 guaranteed to not fail.
            return *swl.getValue();
        }
    }
    return *_defaultLanguage;
}