Task: Receive a Mattermost message when a user updates their profile on Facebook

n8n workflow JSON:
{"id":"131","name":"Receive a Mattermost message when a user updates their profile on Facebook","nodes":[{"name":"Facebook Trigger","type":"n8n-nodes-base.facebookTrigger","position":[590,260],"webhookId":"14ba2eea-04a1-4659-b83e-0090ba480452","parameters":{"appId":"","options":{"includeValues":true}},"credentials":{"facebookGraphAppApi":"facebook"},"typeVersion":1},{"name":"Mattermost","type":"n8n-nodes-base.mattermost","position":[790,260],"parameters":{"message":"=The user with uid {{$node[\"Facebook Trigger\"].json[\"uid\"]}} changed their {{$node[\"Facebook Trigger\"].json[\"changes\"][0][\"field\"]}} to {{$node[\"Facebook Trigger\"].json[\"changes\"][0][\"value\"][\"page\"]}}.","channelId":"13fx8838gtbj3d41a6a7c1w7fe","attachments":[],"otherOptions":{}},"credentials":{"mattermostApi":"mattermost"},"typeVersion":1}],"active":false,"settings":{},"connections":{"Facebook Trigger":{"main":[[{"node":"Mattermost","type":"main","index":0}]]}}}