docs: private static Set<Class<?>> collectConverterClass(String scanPackageName) {
          Set<Class<?>> set = ClassUtil.getClassSet(scanPackageName);
          if (CollectionUtils.isEmpty(set)) {
              return Collections.emptySet();
          }
          Predicate<Class<?>> predicate = clazz -> clazz.isAnnotationPresent(Converter.class);
          return set.parallelStream().filter(predicate).collect(Collectors.toSet());
      }