Build fails on undertow example with an error related to Multi-release module

[antoinesd]

Building the project fails with following error:

Error: jboss-logging-3.2.1.Final.jar is a multi-release jar file but --multi-release option is not set

while boss-logging is not a multi-release module.

[gunnarmorling]

Hey @antoinesd, so I think this is caused by the recently resolved issue #67. By default the generated module-info.class is located under META-INF/versions/9 now, which causes problems when subsequently using jdeps (as implicitly done by the generate-module-info / add-module-info goals). So it seems using META-INF/versions/9 by default turns out to not be a good idea, as it'd break the usage of ModiTect in many cases. Of course the value can still be given explicitly via the jvmVersion plug-in option. (CC @lukehutch)

[gunnarmorling]

Resolved via #73.

[lukehutch]

If a jarfile does not contain a Multi-Release: true entry in its manifest file, it is not a multi-release jar (confirmed with Alan Bateman), and anything in META-INF/versions/ should be ignored. Is the jdeps tool itself not honoring this?

[gunnarmorling]

There is a bug in jdeps which prevents it from running with a mixture of MR JARs and non-MR JARs.

We run into this when adding module descriptors to existing JARs (typically dependencies you'd like to use in a jlink image). After adding a descriptor under META-INF/versions/9 to the first dependency, the jdeps call to subsequent ones (for creating the candidate descriptor) failse due to that. As I learned, this has been fixed in JDK 12 and also be backported to the upcoming 11.0.2 release, i.e. then things can be made working by passing the --multi-release=xyz option to the jdeps call.

[gunnarmorling]

So I'll reopen this and assign to the next release, making sure we pass the --multi-release option to the jdeps call if needed.

[whiskeysierra]

This seems to work with jdeps from JDK 11 and onwards. But then I'm having an issue when I try to produce a Java-9-compatible module-info, because moditect generates a module-info.class with a major version 55 (which is Java 11).

Is there a way to use a newer JDK to produce a Java-9 module-info.class?

[whiskeysierra]

Is there a way to use a newer JDK to produce a Java-9 module-info.class?

Nevermind. Setting jvmVersion to 9 works.