How to avoid forced mapping in http request

I am making a http request to create a trigger in zendesk.

This is my body part.

What I want is like bellow and leave the {{}} part as string. How can I achieve that?

{
  "trigger": {
    "actions": [
      {
          "field": "notification_zis",
          "value": [
            "slack",
            "channel_id",
            "{{6.channel}}",
            "{{ticket.requester.organization.name}}'s {{ticket.requester.name}} is contacting.",
            "<https://{{ticket.url}}|*{{ticket.title}}*>\n*requester*: {{ticket.requester.name}}\n*name*: {{ticket.requester.organization.name}}\n*person in charge*: {{ticket.group.name}}/{{ticket.assignee.name}}\n*explanation*: \n{{ticket.latest_comment}}\n"
          ]
        }
    ],