In a Firebase A/B test, how exactly can you target a specific app version on Android?

In "Targeting" section of a Firebase A/B test, you should be able to target by version:

The version of the app (can vary by platform)

Is this supposed to use versionCode or versionName on Android? Simple question, yet I can't find the answer anywhere, and the documentation is useless in this regard.

My initial assumption was that of course it uses the numeric version code (e.g. 789). But I've tried both that and version name (e.g. 5.5.1), and neither seems to work — "0 users exposed"! (Or the delay before the report updates is very long.)

I've also been assuming that Firebase SDK automatically reads the version info, and it's not up to you as developer to programatically set it, but please correct me if I'm wrong!

I'm using Remote Config based A/B tests, should it make any difference.

Right, turns out it uses versionName. (Experiment data was coming in with a long delay so it was hard to tell.)

You can use exact matches, "contains", and regexes: