code: public @NotNull LinkArgs properties(Map<String, Object> map) {
      if (map == null) {
        throw new IllegalArgumentException("Map argument must not be null.");
      }
      getProperties().putAll(map);
      return this;
    }
docs: Custom properties that my be used by application-specific markup builders or processors.
  @param map Property map. Is merged with properties already set.
  @return this