The error message mentions updating assets "Exception in thread "main" java.io.IOException: PUT operation to URL https://my-nexus.com/repository/releases-sandbox/com/foo/pants/play-gen-tools/0.0.113/jars/play-gen-tools.jar failed with status code 400: Repository does not allow updating assets: releases-sandbox" however I use

./pants publish pants-plugins/scala/play-gen-tools --no-publish-jar-dryrun --no-publish-jar-commit --no-publish-jar-prompt -ldebug --publish-jar-override=com.foo.pants#play-gen-tools=0.0.113

And I change the overrided version for each test