An android app can have one version name (for instance: 2.2.1) for several version code (134 and 135 for instance), and it could be handy to filter events by version code.

Could be added here: https://github.com/mixpanel/mixpanel-android/blob/master/src/main/java/com/mixpanel/android/mpmetrics/MixpanelAPI.java#L1008