The new message format needs to take into account that we have a list of things (policies, recommendation) now, and we need to prepare to have metadata about each individual "thing", we may want to add a "level" per "thing" later on, so that people can subscribe only to "things" of a particular level, or we may want to add a "resource_id" so that people can say for "resource_id" "x" ping some particular people.
We only need to be prepared for the extra metadata so that the format won't change.

So something like this (There may be better names for "items","metadata" and "payload")

{
 "bundle": "rhel",
 "application": "policies",
 "event_type": "policy-triggered",
 "timestamp": "2020-12-08T09:31:39Z",
 "account_id": "000000",
 "items": [
 { 
 "metadata": \{ "future" : "proof" },
 "payload": \{ "any" : "thing", "we": 1, "want" : "here" }
 },
 { 
 "metadata": \{ "future" : "proof" },
 "payload": \{ "any" : "thing", "we": 1, "want" : "here" }
 }]
}