Function operator+=

3rd/nlohmann_json/include/nlohmann/json.hpp:5478–5482

! @brief add an object to an array @copydoc push_back(basic_json&&) */

    @copydoc push_back(basic_json&&)
    */
    reference operator+=(basic_json&& val)
    {
        push_back(std::move(val));
        return *this;
    }

    /*!
    @brief add an object to an array