Method emplace

src/utils/json.hpp:16424–16435

        : Container{init, alloc} {}

    std::pair<iterator, bool> emplace(const key_type& key, T&& t)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
        {
            if (it->first == key)
            {
                return {it, false};
            }
        }
        Container::emplace_back(key, t);
        return {--this->end(), true};
    }

    T& operator[](const Key& key)
    {