In any case, the workaround at that time was to run Notes in Basic Mode, which effectively reverts Notes to running the old Release 7 Notes client written in C++, naked of the Expeditor wrapper that provides the new features of Notes that debuted in Release 8. In Basic Mode, Notes does not use any Java-based features.
Another odd thing that I discovered since writing my last post is that the Notes 9.0.1 installer for the MacOS platform is "broken" with respect to MacOS High Sierra. The first time you run it on a machine running MacOS, it fails in the Provisioning stage, with the following error message:
File /Applications/IBM Notes.app/Contents/MacOS/rcp/rcplauncher.properties not found. Provisioning process failed to launch or was terminated before status could be determined.Then the installation fails.
The fix for this is, of all things, to rerun the installer. The second time around it succeeds all the way through. Go figure.