Route Details: 
Route name: api.messenger.threads.add.participants
URI: api/messenger/threads/{thread}/add-participants
Methods: GET|HEAD
Example Query:
http://messenger.test/api/messenger/threads/9626c1a5-72a7-4b15-aa10-b4bfa368e218/add-participants
GET 403: 

Response:

    {
    "message": "Not authorized to add participants."
}
GET 200: 

Response:

    [
    {
        "party": {
            "name": "John Doe",
            "route": null,
            "provider_id": "9626c1a5-7182-46fa-a16b-1982c5a7bbab",
            "provider_alias": "user",
            "base": {
                "id": "9626c1a5-7182-46fa-a16b-1982c5a7bbab",
                "name": "John Doe",
                "picture": null,
                "created_at": "2022-04-26T00:13:37.000000Z",
                "updated_at": "2022-04-26T00:13:37.000000Z"
            },
            "options": {
                "can_message_first": true,
                "friendable": true,
                "can_friend": true,
                "searchable": true,
                "can_search": true,
                "online_status": 0,
                "online_status_verbose": "OFFLINE",
                "friend_status": 1,
                "friend_status_verbose": "FRIEND",
                "last_active": "2022-04-26T00:13:37.000000Z",
                "friend_id": "9626c1a5-7300-4631-8c69-b3d319ca5047"
            },
            "avatar": {
                "sm": "\/messenger\/assets\/provider\/user\/9626c1a5-7182-46fa-a16b-1982c5a7bbab\/sm\/default.png",
                "md": "\/messenger\/assets\/provider\/user\/9626c1a5-7182-46fa-a16b-1982c5a7bbab\/md\/default.png",
                "lg": "\/messenger\/assets\/provider\/user\/9626c1a5-7182-46fa-a16b-1982c5a7bbab\/lg\/default.png"
            }
        },
        "type_verbose": "FRIEND",
        "id": "9626c1a5-7300-4631-8c69-b3d319ca5047",
        "owner_type": "users",
        "owner_id": "9626c1a5-712e-4e9a-8b8c-46bf71f5ba8a",
        "party_type": "users",
        "party_id": "9626c1a5-7182-46fa-a16b-1982c5a7bbab",
        "created_at": "2022-04-26T00:13:37.000000Z",
        "updated_at": "2022-04-26T00:13:37.000000Z"
    }
]