Custom REST sensor for to pull our the last json array value

Dear community.

i have an api that i need to pull from it some metric json data. the issue is that the API can allways return me the last 30 min. i need to find a way to take the last json array value ( which has the last updated value) -see image on the below link

• https://fileportal.supportservices.asia/Handlers/AnonymousDownload.ashx/1.png?file=3bc06269

i used this Extraction query to pull our the last timeslices $.metric_data.metrics[0].timeslices[(@.length-1)].values see below link

• https://fileportal.supportservices.asia/Handlers/AnonymousDownload.ashx/2.png?file=78def3ea

now how can i implemant this with Custom Rest senson , i dindnt manage to create a good tamplate scrip to do this. from the last value i want to pull only average_response_time and requests_per_minute

[
    {
        "average_response_time": 13.9,
        "calls_per_minute": 289,
        "call_count": 289,
        "min_response_time": 7.34,
        "max_response_time": 147,
        "average_exclusive_time": 13.9,
        "average_value": 0.0139,
        "total_call_time_per_minute": 4.04,
        "requests_per_minute": 289,
        "standard_deviation": 11.5
    }
]

appreciate your help on this

custom-sensor jsonpath rest