DBusConnection.getPeerCredentials

Gets the credentials of the authenticated peer. This will always return null unless connection acted as a server (e.g. [gio.types.DBusConnectionFlags.AuthenticationServer] was passed) when set up and the client passed credentials as part of the authentication process.

In a message bus setup, the message bus is always the server and each application is a client. So this method will always return null for message bus clients.