Function add

src/ArduinoJson/Array/JsonArray.hpp:48–50

  template <typename T, detail::enable_if_t<
                            !detail::is_same<T, JsonVariant>::value, int> = 0>
  T add() const {
    return add<JsonVariant>().to<T>();
  }

  // Appends a new (null) element to the array.
  // Returns a reference to the new element.