Use Google Chat webhook API to send message to channel

Sending message to the Google Chat (chat.google.com, recently integrated to mail.google.com/chat/) is surprisingly simple with their webhook API. Just took me some time to figure out a data structure to send (although it it very simple as I found on Incoming webhook with Python page):

curl -X POST -H "Content-Type: application/json; charset=UTF-8" --data '{"text": "Hello @jhutar, how are you?"}' "https://chat.googleapis.com/v1/spaces/.../messages?key=...&token=..."
{
  "name": "spaces/.../messages/...",
  "sender": {
    "name": "users/...",
    "displayName": "Jenkins incomming webhook",
    "avatarUrl": "",
    "email": "",
    "domainId": "",
    "type": "BOT",
    "isAnonymous": false
  },
  "text": "Hello @jhutar",
  "cards": [],
  "previewText": "",
  "annotations": [],
  "thread": {
    "name": "spaces/.../threads/..."
  },
  "space": {
    "name": "spaces/...",
    "type": "ROOM",
    "singleUserBotDm": false,
    "threaded": true,
    "displayName": "Name of the channel"
  },
  "fallbackText": "",
  "argumentText": "Hello @jhutar, how are you?",
  "attachment": [],
  "createTime": "2021-10-11T22:07:39.490063Z",
  "lastUpdateTime": "2021-10-11T22:07:39.490063Z"
}