[TLDR: Piotr and I propose moving `log4j-jmx-gui` to its own repository to ease Java 9+ migration for `2.x`, objections?]
In the `2.x` branch, AFAIK, `log4j-jmx-gui` is the only module that has a Java 8 requirement, i.e., `jconsole.jar`. Piotr and I have been trying to come up with ways to make `2.x` use a Java 9+ compiler (be it 11 or 17), though every solution we have come up with has certain limitations due to this `jconsole.jar` requirement. I want to propose moving `log4j-jmx-gui` to its own repository. For one, we _can_ simply remove it from `2.x` for the time being and postpone the new repository bootstrapping until there is a need to make a change to `log4j-jmx-gui`. (Please note that I mention this for its implementation convenience, not as a requirement.) Second, we _might_ break some users' workflow. Once the module is moved to its own repository, it will have a separate release lifecycle, hence, we should ideally remove it from `log4j-bom`. Users who run `log4j-jmx-gui` through the dependency provided by `log4j-bom` will have a problem. Imagine we release `log4j-bom` 2.21.0 that doesn't ship a `log4j-jmx-gui` dependency. Piotr and I think that probably almost all `log4j-jmx-gui` users provide an explicit version, hence our inclination for this breaking change. Objections?
