in src/main/java/org/apache/commons/validator/ValidatorResources.java [345:350]
private String buildLocale(final String lang, final String country, final String variant) {
final StringBuilder key = new StringBuilder().append(lang != null && !lang.isEmpty() ? lang : "");
key.append(country != null && !country.isEmpty() ? "_" + country : "");
key.append(variant != null && !variant.isEmpty() ? "_" + variant : "");
return key.toString();
}