in locales-common/src/main/java/com/spotify/i18n/locales/common/model/ResolvedLocale.java [208:217]
private static void validateLocaleForTranslations(ResolvedLocale resolvedLocale) {
Preconditions.checkState(
!resolvedLocale.localeForTranslations().equals(ULocale.ROOT),
"The given localeForTranslations cannot be the root.");
Preconditions.checkState(
SupportedLocale.ALL_AVAILABLE_LOCALES.contains(resolvedLocale.localeForTranslations()),
"The given localeForTranslations %s must be canonical and available in CLDR.",
resolvedLocale.localeForTranslations().toLanguageTag());
}