code: public static Field[] get(Class<?> clazz) {
          Field[] fields = CACHED_FIELDS.get(clazz);
          if (fields == null) {
              fields = clazz.getFields();
              CACHED_FIELDS.putIfAbsent(clazz, fields);
          }
  
          return fields;
      }
docs: Get fields of the given class.
  @param clazz the class
  @return the fields of the given class