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Mattermost, Inc.

Webhooks - Json table in "text": parameter

The answer here may be a simple ‘this is not supported’ but I’ve got an incoming webhook with a payload that defines the text as a json table. I.e.
{
“username”:“User”,
“icon_url”:“Image.png”,
“text”:{
“rows”:[
{
“items”:[
“10:42:41 UTC”,
“hostname”
],
“message”:“Error message 1”
},
{
“items”:[
“10:42:41 UTC”,
“Hostname”
],
“message”:“Error message 2”
}
],
“columns”:[
“Time”,
“Host”
],
“label”:“Sample Logs”
}
}

This payload triggers a 400 response, “unable to parse data”, yet a json syntax checker says it’s OK.

Can I define a json table within the “text”: parameter of an incoming Webhook or can I only use Markdown for the text parameter?