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https://issues.apache.org/jira/browse/MASSEMBLY-891?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16547566#comment-16547566
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Joachim Sauer commented on MASSEMBLY-891:
-----------------------------------------
I've since realized that this problem will only occur when running Maven using
Java 10 (possibly Java 9 as well, haven't tried that). Switching the build to
use Java 8 "fixed" the issue, which is a little unexpected.
> Multi-release JAR files aren't handled correctly
> ------------------------------------------------
>
> Key: MASSEMBLY-891
> URL: https://issues.apache.org/jira/browse/MASSEMBLY-891
> Project: Maven Assembly Plugin
> Issue Type: Bug
> Affects Versions: 3.1.0
> Reporter: Joachim Sauer
> Priority: Major
>
> Apparently there's now a thing called a multi-release JAR where a JAR file
> can contain multiple copies of the same class, where some are used only on
> certain Java versions and up (starting with Java 9):
> [http://openjdk.java.net/jeps/238]
>
> Sounds like a neat idea. For backwards compatibility all the "old" class
> files are where they always used to be and new ones are placed under
> META-INF/versions/<javaVersion>/
> log4j-api-2.9.1.jar is such a multi-release jar and works just fine.
>
> However, when building a jar-with-dependencies it seems that the "regular"
> class file gets overwritten with the Java 9 version of the class file for
> some reason.
> Looking at log4j-api-2.9.1:
> {{$ unzip -l log4j-api-2.9.1.jar | grep StackLocator.class}}
> {{ 6336 2017-09-17 22:52
> org/apache/logging/log4j/util/StackLocator.class}}
> {{ 7264 2017-09-17 22:52
> META-INF/versions/9/org/apache/logging/log4j/util/StackLocator.class}}
> Looking at the jar-with-dependencies produces by maven-assembly-plugin 3.1.0:
> {{unzip -l target/myproject-0.0.1-SNAPSHOT-jar-with-dependencies.jar | grep
> StackLocator.class}}
> {{ 7264 2017-09-17 22:52
> org/apache/logging/log4j/util/StackLocator.class}}
> {{ 7264 2017-09-17 22:52
> META-INF/versions/9/org/apache/logging/log4j/util/StackLocator.class}}
> Now obviously the best fix would be to make maven-assembly-plugin fully
> Multi-release compatible and even write the correct META-INF/MANIFEST.MF
> Entry to make it work, but as an intermediate step even just keeping the
> original version as provided and not overwriting it with the Java 9 version
> would be an improvement.
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