Set Automatic-Module-Name and fix maven-enforcer-plugin problem

[ljnelson]

This PR bumps the version of the maven-enforcer-plugin so that it can cope with the version strings of modern JDKs and won't exit with an ExceptionInInitializerError when invoked. It also sets an Automatic-Module-Name in the META-INF/MANIFEST.MF file. I followed the module naming guidelines referenced by Stephen Coleburne here: https://blog.joda.org/2017/04/java-se-9-jpms-module-naming.html

This is obviously a stopgap measure until this library can be truly modularized but it at least "claims" the module name with no compatibility issues.

Signed-off-by: Laird Nelson ljnelson@gmail.com

[n1hility]

Thanks for the PR. I think this is reasonable.

FWIW I think it's unlikely that Jandex will ever utilize Java modules beyond this. It supports pre Java 9 vms (as far back as Java 6), and for Java 9+ we also wish to support common classpath usage. While you can add a modules descriptor and let it be ignored, that also means that any security or isolation is also ignored, so it's best to just rely on package security.