[Bug] Incoming Webhook broken

Description:

Since upgrading to 3.16+ it seems some Slack-compatible Incoming Webhooks seem to not work any more. There isn't much detail other than what I can provide below with screenshots and relevant logs.

Steps to reproduce:

1. Setup Channel and add user(s) to Channel
2. Setup Integration to use that channel
3. Copy Webhook URL to app to send webhooks to Rocket.Chat

Expected behavior:

Webhook post content to channel

Actual behavior:

No content shows

Server Setup Information:

• Version of Rocket.Chat Server: 3.18.1
• Operating System: Ubuntu 18.04
• Deployment Method: docker
• Number of Running Instances: 1
• DB Replicaset Oplog: Enabled
• NodeJS Version: v12.22.1
• MongoDB Version: 4.0.17 / mmapv1 (oplog Enabled)

Client Setup Information

• Desktop App or Browser Version: Latest Linux Electron App
• Operating System: Pop!_OS!

Additional context

Relevant logs:

I20210915-14:57:17.184(0) Integrations ➔ Incoming WebHook.info Post integration: SupportPal Dev
I20210915-14:57:17.186(0) Integrations ➔ Incoming WebHook.debug @urlParams: { integrationId: 'AfWf54ZnXqAJf6nWF', token: 'nN2stSRrpENZdRzD3birmM28qT9WGTeKTvScf7HBDFQhAoc8' }
I20210915-14:57:17.187(0) Integrations ➔ Incoming WebHook.debug @bodyParams: {}
I20210915-14:57:17.188(0) API ➔ debug Success { statusCode: 200, body: { success: true } }
I20210915-14:57:17.189(0) API ➔ info 10.200.X.XXX - aDFNiCQWGwZX7ATD9 [2021-09-15T14:57:17.188Z] "POST /hooks/AfWf54ZnXqAJf6nWF/nN2stSRrpENZdRzD3birmM28qT9WGTeKTvScf7HBDFQhAoc8" 200 - "undefined" "GuzzleHttp/6.5.5 curl/7.58.0 PHP/7.2.24-0ubuntu0.18.04.8" |
I20210915-14:57:23.792(0) API ➔ debug Success { statusCode: 200, body: { queue: [ [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], [Object], ... 900 more items ], success: true } }

I20210915-14:58:37.488(0) Integrations ➔ Incoming WebHook.info Post integration: SupportPal Dev
I20210915-14:58:37.489(0) Integrations ➔ Incoming WebHook.debug @urlParams: { integrationId: 'AfWf54ZnXqAJf6nWF', token: 'nN2stSRrpENZdRzD3birmM28qT9WGTeKTvScf7HBDFQhAoc8' }
I20210915-14:58:37.490(0) Integrations ➔ Incoming WebHook.debug @bodyParams: {}
I20210915-14:58:37.491(0) API ➔ debug Success { statusCode: 200, body: { success: true } }
I20210915-14:58:37.492(0) API ➔ info 10.200.X.XXX - aDFNiCQWGwZX7ATD9 [2021-09-15T14:58:37.491Z] "POST /hooks/AfWf54ZnXqAJf6nWF/nN2stSRrpENZdRzD3birmM28qT9WGTeKTvScf7HBDFQhAoc8" 200 - "undefined" "GuzzleHttp/6.5.5 curl/7.58.0 PHP/7.2.24-0ubuntu0.18.04.8" |
I20210915-14:59:00.239(0) SyncedCron ➔ info Starting "Federation".

Reproduce the POST to the /hooks/{integrationId}/{token} endpoint using the server setup described, and inspect the Incoming WebHook logs where bodyParams is empty despite a successful response. Trace why the webhook payload is not posted to the configured channel; done means a Slack-compatible webhook's content appears in that channel.