I have registered an [Incoming Messages Webhook](https://learn.microsoft.com/en-us/microsoftteams/platform/webhooks-and-connectors/how-to/add-incoming-webhook#:%7E:text=Incoming%20Webhook%20allows%20any%20external,a%20message%20in%20card%20format.) in one of my Teams channels.
I am using [Microsoft Teams PowerShell](https://learn.microsoft.com/en-us/powershell/teams/?view=teams-ps) to create an adaptive card and send it to a channel:

```
$SimpleCard = @{
    type = "message";
    attachments = @(@{
        contentType  = 'application/vnd.microsoft.card.adaptive';
        contentUrl = $null;
        content = @{
            '$schema' = 'http://adaptivecards.io/schemas/adaptive-card.json';
            type = 'AdaptiveCard';
            version = '1.2';
            body = @(@{
                type = 'TextBlock';
                text = "Hello <at>andrea.tino@mycompany.com</at>";
            })
        }
    });
    msteams = @{
        entities = @(@{
            type = 'mention';
            text = "<at>andrea.tino@mycompany.com</at>";
            mentioned = @{
                id = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx";
                name = 'Andrea Tino';
            }
        })
    }
}

Invoke-RestMethod -Method post
                  -ContentType 'Application/Json'
                  -Body ($SimpleCard | ConvertTo-Json -Depth 10)
                  -Uri "https://myorg.webhook.office.com/webhookb2/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx@xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/IncomingWebhook/xxxxxxxx/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"

```

The card is correctly sent but the mention is not correctly rendered.

Wrong ID?
---------

It is worth mentioning that [the doc](https://learn.microsoft.com/en-us/microsoftteams/platform/task-modules-and-cards/cards/cards-format?tabs=adaptive-md%2Cconnector-html#sample-adaptive-card-with-a-mention) makes explicit reference to a type of User ID:

```
{
  "type": "mention",
  "text": "<at>John Doe</at>",
  "mentioned": {
    "id": "29:123124124124",
    "name": "John Doe"
  }
}

```

You can see that the ID in the example is: `"id": "29:123124124124"` while mine is a GUID. I retrieved that User ID by means of [`Get-TeamUser`](https://learn.microsoft.com/en-us/powershell/module/teams/get-teamuser?view=teams-ps).

What am I doing wrong?