javafxpackager usually creates bundles with the version like "packagename-1.0.deb" or "packagename-1.0.rpm", but for mac it creates just "packagename.dmg".

Is it a regression: no.
Steps to reproduce: create any java project and run "javafxpackager -makeall -appclass Main -name Main", package and appclass doesn't matter.
Expected result: "Main-1.0.dmg"
Actual result: "Main.dmg"