After adding MR-JAR support with
LUCENE-7966, we should test the release candidates with Java 9. Therefore the already existing code in build.xml that uses a separate environment variable to pass JAVA9_HOME should be reenabled. This also requires reconfiguring Jenkins.
- is superceded by
LUCENE-8241 Improve Smoketester to test multiple JDK versions
- relates to
LUCENE-7966 build mr-jar and use some java 9 methods if available