docs: public JsonObject add(String name, JsonValue value) {
      if (name == null) {
        throw new NullPointerException(NAME_IS_NULL);
      }
      if (value == null) {
        throw new NullPointerException(VALUE_IS_NULL);
      }
      table.add(name, names.size());
      names.add(name);
      values.add(value);
      return this;
    }