MarsSeed [1] filed a deletion request for java8-openjdk-shenandoah [2]: This experimental JDK8 variant with backported Shenandoah GC to JRE8 seems not to be updated anymore by upstream.
Not useful to enhance and maintain this package. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/java8-openjdk-shenandoah/
