transition.urlMethod as a proxy for browser pop state?

I'm using the new Ember 3.7 routerService to build the browser's history in js-land for the purposes of showing nav back/forward buttons (think iOS app nav buttons).

One issue I'm facing is when to detect that a `routeDidChange` was the consequence of a browser back/forward event.

This can be known if I hook into the `window.onpopstate` event, but unfortunately, this fires after `routeDidChange`.

So, I've delved into the transition object in the hope of some clue as to whether a specific transition was browser initiated rather than a usual ember routing event.

It seems that `transition.urlMethod` may be this, from my limited testing it seems that `transition.urlMethod` will be `null` when a browser back/forward action triggered the transition and I can therefore use a null value as a indication that some kind of back/forward was used.

I've searched the codebase to see whether this is a safe assumption, but it seems that none of the comments specifically identify this.

So my question is... can I safely use `transition.urlMethod` to indicate in my code that a transition was not triggered by Ember and therefore is likely a browser-triggered back/forward transition?