in locales-common/src/main/java/com/spotify/i18n/locales/common/impl/LocalesResolverBaseImpl.java [405:414]
private String overrideLanguageRangeBasedOnDefaultLocale(
final String languageRange, final ResolvedLocale defaultResolvedLocale) {
return Optional.of(languageRange)
.filter(lr -> lr.contains("-"))
.map(
lr ->
defaultResolvedLocale.localeForTranslations().getLanguage()
+ lr.substring(lr.indexOf("-")))
.orElse(defaultResolvedLocale.localeForTranslations().getLanguage());
}