While building some artifacts of the version 2.6.0 I found trouble with maven saying the pom of that dependency its invalid.
Problem was encoding ISO-8859-1 instead of UTF-8 in the mentioned version, its fixed in the next versions tough.
Tested with maven 3.9.2.
Two workarounds:

• update the dependency in spoofax-deploy/parent/pom.xml to a more recent version or
• (not suggested but works) change the encoding in .m2/repository/org/codehaus/mojo/build-helper-maven-plugin/3.0.0/build-helper-maven-plugin-3.0.0.pom once maven has downloaded it.

I was building dependencies needed for spt.cmd and found that error, also when the build it’s successful there are some warnings about prettyprinter but thats enought for me.
The spoofax-deploy repo hasn’t issues enabled so I’m writting here, I think it’s the correct place.

Submitted by Luis Tapia on 23 May 2023 at 06:57

I missed the pom
spoofax-deploy/parent/pom.xml

Sorry for the late response. This is a known issue with Maven 3.9.x versions, please downgrade to Maven 3.8.8. This is now documented here.
We hope to support Maven 3.9 and up at a later point.