Google IAP v3 - 'cancelled' state isn't triggered

Solar2D Monetization (in-app purchases, ads, etc.)
#1

I have integrated IAP v3 api in my Android app, and it is mostly working fine.

One problem I have is that once I’ve entered the Google payment flow (e.g. entering the password to authorize the purchase), hitting the hw ‘back’ button will not  generate the expected transition state ‘cancelled’ to my transaction callback. 

Instead my callback gets a ‘failed’ state with errorType: -1005 and errorString: “User canceled. (response: -1005:User cancelled)”

Isn’t 'cancelled the expected state here?

Thanks,

Johan