Cannot resolve heartbeat fields in alerting annotations

Hello everyone in the community,

I have created a panel receiving from elastic search ← heartbeat, grouping by “" and “url.full”,

I want to pass these two fields in annotation with the config:
"Resources" {{$}} {{$labels.url.full}}

fyr: Annotations and labels for alerting rules | Grafana documentation

However, the contents are not able to passed and as ‘.’, in the variable name.

"annotations": {
          "Resources": "<no value>  <no value>",

I have already tried several methods, for example
adding \ in front of “.”,
{{$labels.“”}} {{$labels.“url.full”}} etc

and none of them is working. I will be greatly appreciate if anyone could tell me a solution. Many thanks!

Versions used :
Grafana : 8.5.2

Please help, appreciate!

Please help, appreciate!