call_rejected event

If a Call has been shared with a user in DM (and unfurled with the help of the link_shared event) this event is sent if the user rejects the Call.

Here's an example payload:

{
    "token": "12345FVmRUzNDOAu12345h",
    "team_id": "T123ABC456",
    "api_app_id": "BBBU04BB4",
    "event": {
        "type": "call_rejected",
        "call_id": "R123ABC456",
        "user_id": "U123ABC456",
        "channel_id": "D123ABC456",
        "external_unique_id": "123-456-7890"
    },
    "type": "event_callback",
    "event_id": "Ev123ABC456",
    "event_time": 1563448153,
    "authed_users": ["U123ABC456"]
}