docs: public static Set<Locale> getLocalizationProblemLocales( Class<?> i18nClass ) {
          CheckArg.isNotNull(i18nClass, "i18nClass");
          Set<Locale> locales = new HashSet<Locale>(LOCALE_TO_CLASS_TO_PROBLEMS_MAP.size());
          for (Entry<Locale, Map<Class<?>, Set<String>>> localeEntry : LOCALE_TO_CLASS_TO_PROBLEMS_MAP.entrySet()) {
              for (Entry<Class<?>, Set<String>> classEntry : localeEntry.getValue().entrySet()) {
                  if (!classEntry.getValue().isEmpty()) {
                      locales.add(localeEntry.getKey());
                      break;
                  }
              }
          }
          return locales;
      }