Thanks to everyone for all the feedback on this topic. It appears that issuing warning messages for illegal-access operations enabled by the precise `--add-opens` and `--add-exports` options is a bit too aggressive, at least for JDK 9. Perhaps we can enable that in JDK 10 after there's been more time for libraries, frameworks, and even the JDK itself to adjust to the realities of strong encapsulation.
For now I suggest that we revert to the previous behavior of these two options, so that they do not cause warning messages to be issued. The new `--permit-illegal-access` option will continue to generate warning messages, as proposed. If those messages are a problem in a particular scenario then they can be eliminated by switching to an appropriate set of `--add-opens` options, which can be constructed from the information contained in those messages. Comments? - Mark