Ignore /META-INF/versions/9/module-info.class by default

[Mortinke]

We have the same issue with /META-INF/versions/9/module-info.clas files as in #31.
e.g. https://travis-ci.org/zalando/logbook/jobs/448681344 or #31 comment

[mpellegrini]

Wondering if the mentioned PR mentioned above would get merged?

[hgschmie]

Hi, thanks for the ping. This is related to multi-release jars and requires a more comprehensive change to the plugin. I am planning to do this when I find time.

As a workaround, you can add this pattern in your pom as well.

[mpellegrini]

Thanks for the quick reply. I have added the ignore pattern to my pom for the time being.

Thanks for your work on producing a very useful plugin!!

[stevenschlansker]

This problem is continuing to spread -- latest releases of very popular jars like assertj and byte-buddy now conflict with each other.

[hgschmie]

I need to find time to work out how to deal with multi-release jars. PRs very welcome

[hgschmie]

This is fixed in the next version. I am planning that the next version will be the last one that runs on JDK8 and the one after will be JDK9+ exclusive.

In that version, I am planning to do more work with multi-release jars; currently there is a corner case where a duplicate class is not detected:

Base jar contains no conflicts
  |
  +-- META-INF/versions/9/A.class    is a conflict with an existing class on the class path

the current plugin would not detect this conflict when running under JDK9. To be able to manage these type of conflicts, the code must analyze the Multi-Release flag from the manifest and then build a map on which classes are actually visible on the class path. Very doable but I see no point in doing this for the JDK 8 version.