Resolution: Won't Do
Luke, a non-Apache-hosted piece of software, is under consideration for donation as a module to the Lucene project: https://issues.apache.org/jira/browse/LUCENE-2562 . Because in its initial incarnation it depended for its UI on Thinlet, which uses a non-Apache-compliant license, it was rewritten to use JavaFX to allow it to be donated to Apache.
With JDK 8 (Lucene's currently supported Java version), JavaFX/OpenJFX is shipped inside rt.jar (i.e. bundled with the Java runtime). On other versions it is not included at all and in Java 10 it's now part of the Java module system.
Starting with Java 11, JavaFX is no longer shipped with the JDK, and will be available via an external dependency available e.g. through Maven Central repository. Related: https://github.com/javafxports/openjdk-jfx/issues/52 ("run JavaFX app using maven/gradle with Java 11")
> OpenJFX is free software, licensed under the GNU General Public License with Classpath Exception, just like the JDK Project.
This license ^ is listed under Category X on https://www.apache.org/legal/resolved.html#category-x , and as a result, once Java 11 (ETA September 2018) becomes a supported Java version by Lucene, which is likely to happen relatively soon given Oracle's new Java versioning policy, Lucene will not be able to release with Luke as a module in its current form.
Can an exception be made for Lucene to include JavaFX/OpenJFX as an external dependency?