Say I have a "public" group in Nexus which contains two repositories "snapshotsA" and "snapshotsB". Both contain versions with the same Maven coordinates, like com.something:artifact:1.0.0-SNAPSHOT. How does Nexus resolve a SNAPSHOT reference? Does it look into both repositories to find the latest element? Or is it satisfied after finding the first one?
For groups in Nexus Repository 2.x, we resolve the first match in the group ordering, unless some sort of Repository Routing or Repository Target rules prevent that from being matched (for example if you know bad versions of that component exist in that repository by not treating components immutably, etc...)
In Nexus Repository 3.x this is currently simpler as we have not implemented Repository Routing. The first match in the group ordering is what you would get back.