Options dictionary is not nil when starting the tunnel via Connect On Demand

For the method:

func startTunnel(options: [String: NSObject]? = nil, completionHandler: @escaping (Error?) -> Void)

Docs say that the options dictionary should be nil whenever the tunnel is started via Connect On Demand. It turns out (iOS 12.2) that this is not true. I have following dictionary passed as an argument:

[
  "ServerAddress": /* */,
  "match-hostname": /* */,
  "AuthMethod": Password,
  "VendorData": {
     /* configuration */
  },
  "is-on-demand": 1
]

Is docs or my configuration wrong?