Heads up to library authors who care whether their libraries are usable from Java.
Normally it doesn’t much matter what Scala version your library is built with, but https://github.com/scala/scala/pull/6531 is unusual, it requires libraries be rebuilt on 2.12.7 to get the benefit of the bugfix.
A real example of library users hitting this problem happened on Akka, https://github.com/akka/akka/issues/25777 (and see also https://github.com/scala/bug/issues/11061). For Java users on JDK 11, an Akka method became uncallable from Java. The problem will be fixed once an Akka version is published that was built with 2.12.7.