This will get you as far as seeing the format/content of the json returned in the "event" object. From there you can start using it
session.onshippingcontactselected = function(event) {
console.log('starting session.onshippingcontactselected');
console.log(event);
}
From the above, I'm getting partial address values returned in a event.shippingContact object, but I stress *partial*. It's currently missing the name (familyName, givenName), street address and truncating the postalCode to the first 4 chars only.
NB though, that when I include
requiredShippingContactFields: ['postalAddress']
in the paymentrequest it's currently (iOS10b4 and iOS10b3) causing the payment sheet to no longer show "Pay with touch id". instead it's hanging on the preceeding "Processing" stage