bsl::vector<Json>::emplace_back

Append to the end of this vector a newly created value_type object, constructed by forwarding get_allocator() (if required) and the specified (variable number of) arguments to the corresponding constructor of value_type. Return a reference providing modifiable access to the inserted element. If an exception is thrown (other than by the move constructor of a non-copy-insertable value_type), *this is unaffected. Throw std::length_error if size() == max_size(). This method requires that the (template parameter) type VALUE_TYPE be move-insertable into this vector and emplace-constructible from arguments (see {Requirements on VALUE_TYPE}).