Cisco Meraki webhooks integration fails when using shared secrets

Hello,

I've been testing the Cisco Meraki webhooks integration lately, and while it works just fine without specifying a shared secret, it stops working immediately once any text is entered in secret_value as described in https://docs.elastic.co/en/integrations/cisco_meraki#configure-the-cisco-meraki-integration

As far as I can tell, this is because Cisco Meraki sends the shared secret as a JSON attribute sharedSecret, as shown in the test-mx-events.json file included in the integration package:

{
    "events": [
        {
            "json": {
                "version": "0.1",
                "sharedSecret": "secret",
                "sentAt": "2021-10-07T08:42:00.926325Z",
[...]

http_endpoint.yml.hbs, on the other hand, looks for the shared secret in a non-existing Authorization header:

{{#if secret_value}}
secret.header: Authorization
secret.value: "{{secret_value}}"
{{/if}}

I'm mostly posting this to see if this is a confirmed bug, before creating an issue on Github, but please let me know if I'm misunderstanding the way the http_endpoint input module works or if anyone else has been able to make this module work with shared secrets. Thank you!