[MBUILDCACHE-91] maven-dependency-plugin:unpack reactor artifactItems have their versions expanded instead of being replaced by 'cache-extension-version'

**[Réda Housni Alaoui](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=ralaoui)** opened **[MBUILDCACHE-91](https://issues.apache.org/jira/browse/MBUILDCACHE-91?redirect=false)** and commented

I have a multi module project where module1 is used as a dependency of `maven-dependency-plugin:unpack` declared in module2.

The plugin configuration in module2 pom.xml looks like this:

```xml

org.apache.maven.plugins
maven-dependency-plugin


unpack-webstart-resources

unpack

generate-resources

${project.build.directory}/generated-resources/com/aqme/module1


${project.groupId}
module1
${project.version}
blob






```

The effective pom computed by version 1.1.0 of this extension contains `project.version` of artifactItem#version expanded to its effective value instead of `cache-extension-version`. This leads to cache miss when the only difference is `project.version` effective value.

---
No further details from [MBUILDCACHE-91](https://issues.apache.org/jira/browse/MBUILDCACHE-91?redirect=false)

Start with the module2 pom.xml configuration using maven-dependency-plugin:unpack and reproduce the effective POM behavior described for version 1.1.0. Trace how the artifactItems version is expanded, then verify that the cache-extension-version placeholder is preserved and no cache miss occurs when only the effective project.version changes.

Written by the indexing model from the issue text.