I'm happy to discover that ovirt-engine is clean compiled on using jdk9. I
used the official JDK9 container to run it from the repo directory:
docker run -it --rm --name ovirt-engine-compile-jdk9 -v
"$PWD":/usr/src/mymaven -w /usr/src/mymaven docker.io/maven:3-jdk-9 ln -s
/etc/java-9-openjdk /usr/lib/jvm/java-9-openjdk-amd64/conf ; mvn clean
package