[MENFORCER-436] Extension defined in .mvn/extensions.xml failing "requirePluginVersions" check

**[Jeff Thomas](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=jwt007)** opened **[MENFORCER-436](https://issues.apache.org/jira/browse/MENFORCER-436?redirect=false)** and commented

I have defined the "maven-git-versioning-extension' in .mvn/extensions.xml with an explicit version.

 
``
`  `
`    me.qoomon`
`    maven-git-versioning-extension`
`    9.3.1`
`  `
``
This extension is not referenced anywhere in my POM.

However, the 'requirePluginVersions' check is failing during build.

NOTE: I saw MENFORCER-133 which was similiar but is already closed.

Currently I have the workaround to add "me.qoomon:maven-git-versioning-extension" to the "unCheckedPluginList" configuration option, but this is sort of annoying since we use this extension in almost all of our git projects. :)

---

**Affects:** 3.1.0

Start by reproducing the requirePluginVersions failure with the .mvn/extensions.xml configuration and compare the behavior with MENFORCER-133. Inspect how the check handles extensions that are not referenced in the POM; done means the declared extension no longer fails the check without adding it to unCheckedPluginList.

Written by the indexing model from the issue text.