extras-executable-war currently uses sun.misc.Signal, which when combined with release=8 exposes JDK-8206937. To work around that issue, we've temporarily disabled release=8, which is fine as long as we are still supporting Java 8 and using Animal Sniffer. But when we drop support for Java 8 and drop Animal Sniffer, we should restore the use of release=11 (which isn't susceptible to JDK-8206937, either).