The JMX "module" is a debugging module that is delivered as a separate javafx-mx.jar file in JDK/lib. It is currently missing from JDK 9 as of the jigsaw m3 integration.
Comments
Given that this jar file was present, but not supported in JDK 8, and that it is only a developer tool (with limited use), we are going with a variant of option #1. We will no longer deliver javafx-mx.jar along with the JDK, but will continue to build it as part of our developer builds. It will not be included in any promoted builds.
09-09-2016
We have ruled out #3 leaving the following two options:
1) Remove it entirely and drop this tooling support
2) Continue to ship it as a legacy jar file, meaning that any use would require command line qualified exports to be added since it uses internal packages
As such I have removed the "m4" label from this bug. If we go with #2 we will need a way to deliver this, since it wouldn't be part of any existing module.
20-06-2016
I sent the following e-mail to openjfx-dev yesterday:
http://mail.openjdk.java.net/pipermail/openjfx-dev/2016-June/019245.html
I outlined the following three possibilities:
1) Remove it entirely and drop this tooling support
2) Continue to ship it as a legacy jar file, meaning that any use would require command line qualified exports to be added since it uses internal packages
3) Turn it into a proper JDK-only module, javafx.jmx; it would not be one of the default modules, so it would need to be added with -addmods.