Classes for newer versions are not loaded from Multi-Release-JARs in WARs ------------------------------------------------------------------------- Key: WFCORE-4266 URL: https://issues.jboss.org/browse/WFCORE-4266 Project: WildFly Core Issue Type: Bug Components: VFS Environment: Java 9+ Reporter: Daniel Schwering Priority: Major Attachments: buggywar.src.zip, buggywar.war, multireleaselib-0.0.1-SNAPSHOT.jar, multireleaselib-0.0.1-SNAPSHOT.jar, multireleaselib.src.zip, multireleaselib.src.zip 1 down vote favorite Since Java 9 there are Multi-Release JARs ([MRJARS|https://openjdk.java.net/jeps/238]) that allow different classes for different Java versions to be included in one JAR file. I was surprised when a Wildfly 14 running on Java 11 executed Java-8-code in a JAR included in a WAR although the JAR was a MRJAR with code for Java 11. That JAR included as a dependency for a regular Java SE project is running different code depending on the running JRE, but when included in a WAR, the Java-11-code seems to be ignored. Is that expected behavior for a webserver, as Java EE 8 does not explicitly require Java 9 (which introduced MRJARs) but only Java 8?