[MSHADE-367] ServicesResourceTransformer & relocation together cause issues with "reshading"

**[Chris Dennis](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=chrisdennis)** opened **[MSHADE-367](https://issues.apache.org/jira/browse/MSHADE-367?redirect=false)** and commented

The attached sample project shades `org.terracotta:a` in to `org.terracotta:b`. Both a and b declare an implementation of a shared service interface `org.terracotta.Service`. When you `mvn package` this project everything works as it should. If you run `mvn package` again without cleaning first plugin appears to attempt to shade on top of itself and complains that the service file colliides in the JAR file. This issue is hitting us during our build process. We have worked around it by having a task delete the shade output during the pre-package phase but would appreciate a better solution.

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**Affects:** 3.2.3

**Attachments:**
- [maven-shade-bug.zip](https://issues.apache.org/jira/secure/attachment/13003321/maven-shade-bug.zip) (_4.26 kB_)

Start with the attached maven-shade-bug.zip sample project and run mvn package twice without cleaning to reproduce the ServicesResourceTransformer and relocation collision. Trace how the shade output is reused during the second package, then verify that repeated packaging completes successfully and produces the expected shaded JAR without requiring a cleanup task.

Written by the indexing model from the issue text.