The ianal-maven-plugin only had a single pre-release in 2008 (https://www.mojohaus.org/plugins.html). Since then there were no follow-up releases and the source code has not been migrated to GitHub.
Using the plugin leads to warning with Java 11 due to usage of an old version of Groovy.
Other alternatives should be evaluated. This has been discussed in https://lists.apache.org/thread.html/rd7a164cced307aba249dd2ba30d1e7d95db332658fe8b90c4e7d730b%40%3Cdev.sling.apache.org%3E as well.