CardHeader
represents the header of a card. Headers can include a title, subtitle, and avatar-style image.
You can include headers for card messages and dialogs.
Example
The following image displays a card consisting of a CardHeader
component.

CardHeader
displaying a title, subtitle, and icon.
Here's the card's JSON:
JSON
{
"cardsV2": [
{
"cardId": "card_one",
"card": {
"header": {
"title": "Header",
"subtitle": "Subtitle",
"imageType": "SQUARE",
"imageUrl": "https://developers.google.com/chat/images/quickstart-app-avatar.png",
"imageAltText": "Avatar for the card header",
},
}
}
]
}