PHP cURL for modify a guestPass

[TorstenS]

Hello everybody,

i have to modify the propertie "guestName" of a guestPass.

For that i use the API-Endpoint:
/v11_1/identity/guestpass/{userId}

My body looks like that:
$BODY = json_encode([
"guestName"=> 'XYZ',
]);

Now i get the following Error Message:
{ message: 'object instance has properties which are not allowed by the schema: ["guestName"]; ', errorCode: 101, errorType: "Bad HTTP request" }

Can anyone help me please?

Thanks
Torsten