code: private static Locale getAnnotationLocaleValue(
              IAnnotationBinding annotation, String varName) {
          String fieldName = getEnumAnnotationFieldName(annotation, varName);
          if (fieldName == null) {
              return Locale.getDefault();
          }
          Locale resultLocale = Locale.valueOf(fieldName);
          if (resultLocale == null) {
              throw new RuntimeException("invalid locale: " + fieldName);
          }
          return resultLocale;
      }
docs: returns default value if varName value is not specified