Dotty 0.4.0-RC1 shell scripts should detect Java 9 and stop with an error #3304
Description
Dotty won't be compatible with Java 9 until #3138 is done. To avoid confusing people with weird errors, we should check the Java version in the shell script and ask people to use Java 8. To get the Java version use https://github.com/sbt/sbt-launcher-package/blob/master/src/universal/bin/sbt-launch-lib.bash