Does anyone know how to get Kubernetes namespace in webhook alert payload from metricbeat k8s module? Or more generically, how to access the event data to include in the payload?

I installed metricbeat on Kubernetes using this guide: Run Metricbeat on Kubernetes | Metricbeat Reference 7.15 | Elastic

and I got this data:

However, when I created a webhook alert, with this payload to see the all available properties:

alert: {{alert}}
context: {{context}}

This is the only data included:

alert: {\"id\":\"ubuntu\",\"actionGroup\":\"metrics.inventory_threshold.fired\",\"actionGroupName\":\"Alert\"}

context:
{\"group\":\"ubuntu\",\"alertState\":\"ALERT\",\"reason\":\"CPU usage is greater than a threshold of 80 (current value is 99.9%)\",\"timestamp\":\"2021-10-14T22:56:11.799Z\",\"value\":{\"condition0\":\"99.9%\"},\"threshold\":{\"condition0\":[80]},\"metric\":{\"condition0\":\"cpu\"}}

Anyone know how to include the kubernetes.namespace from the source to the alert payload? I need it to be able to identify the pod in the alert uniquely.