webhook at port 9000 (however i use 9090 at gaia.ifong.org # jail www, ipfw.rules foward 9090 into 10.0.0.2
turn on debug  (i use my own starup script at FreeBSD)

note:
1 must https
2 turn the debug on can see userid

/usr/local/sbin/webhook -debug -hooks /usr/local/etc/webhook.yaml -verbose -secure -cert /usr/local/etc/letsencrypt/live/myZone/fullchain.pem -key /usr/local/etc/letsencrypt/live/myZone/privkey.pem -nopanic

[dedcce] {"destination":"U0d873d7cb5","events":[{"type":"message","message":{"type":"text","id":"16096","text":"hi"},"webhookEventId":"01G26MBFRK5","deliveryContext":{"isRedelivery":false},"timestamp":1652273938699,"source":{"type":"user","userId":"U038e4d0f4"},"replyToken":"65dd0eb8c056","mode":"active"}]} #note: i deinfo it, however it is a REAL message