I have just upgraded one of our test Windows Domino Servers from 901FP6 HF310 to 901FP7.
Uninstalled the Hotfix - back to 901FP6
Installed domino901FP7_w64.exe now at 901FP7
I am now used to typing sh jvm after an install and did it by habit, but was surprised at the result.
JVM had been reverted to SR16 FP20
Stopped the Services and had to reapply the latest JVM Patch to get back to SR16 FP30.
Strange thing - The 'Congratulations' message at the end of upgrade to 901FP7 stated that the JVM had not been upgraded.
I hope this helps someone