For reference, an example of adding an XAVP with data pointing to share memory and a callback to free it is at: * https://github.com/kamailio/kamailio/blob/master/src/modules/rtjson/rtjson_r...
Data struct being constructed a bit above there: * https://github.com/kamailio/kamailio/blob/master/src/modules/rtjson/rtjson_r...