ci: check to confirm release versions are not yet published

[suztomo]

suztomo@suztomo:~/migration-work/google-cloud-java/var/suztomo-test/java-spanner$ python3 ../.github/release/check_maven_central.py
Finding pom.xml files...
Found 17 pom.xml files. Parsing unique non-SNAPSHOT artifacts...
Checking 16 unique artifacts on Maven Central...
No published non-SNAPSHOT versions found.
suztomo@suztomo:~/migration-work/google-cloud-java/var/suztomo-test/java-spanner$ cd ../sdk-platform-java/
suztomo@suztomo:~/migration-work/google-cloud-java/var/suztomo-test/sdk-platform-java$ cd java-core
suztomo@suztomo:~/migration-work/google-cloud-java/var/suztomo-test/sdk-platform-java/java-core$ python3 ../.github/release/check_maven_central.py
python3: can't open file '/usr/local/google/home/suztomo/migration-work/google-cloud-java/var/suztomo-test/sdk-platform-java/java-core/../.github/release/check_maven_central.py': [Errno 2] No such file or directory
suztomo@suztomo:~/migration-work/google-cloud-java/var/suztomo-test/sdk-platform-java/java-core$ python3 ../../.github/release/check_maven_central.py
Finding pom.xml files...
Found 5 pom.xml files. Parsing unique non-SNAPSHOT artifacts...
Checking 5 unique artifacts on Maven Central...
[1/5] ALREADY PUBLISHED: com.google.cloud:google-cloud-core-parent:2.67.0
[2/5] ALREADY PUBLISHED: com.google.cloud:google-cloud-core-http:2.67.0
[3/5] ALREADY PUBLISHED: com.google.cloud:google-cloud-core:2.67.0
[4/5] ALREADY PUBLISHED: com.google.cloud:google-cloud-core-bom:2.67.0
[5/5] ALREADY PUBLISHED: com.google.cloud:google-cloud-core-grpc:2.67.0
Summary of published versions found in local pom.xml files:
com.google.cloud:google-cloud-core-bom:2.67.0 (found in ./google-cloud-core-bom/pom.xml)
com.google.cloud:google-cloud-core-grpc:2.67.0 (found in ./google-cloud-core-grpc/pom.xml)
com.google.cloud:google-cloud-core-http:2.67.0 (found in ./google-cloud-core-http/pom.xml)
com.google.cloud:google-cloud-core-parent:2.67.0 (found in ./pom.xml)
com.google.cloud:google-cloud-core:2.67.0 (found in ./google-cloud-core/pom.xml)```

[gemini-code-assist]

Code Review

This pull request introduces a new Python script to verify if Maven artifacts are already published to Maven Central. The review feedback suggests improving the script's robustness by logging errors during POM parsing and network requests, and updating the exit logic to return a non-zero status code when published versions are detected to ensure CI pipelines fail appropriately.

[suztomo]

It needs to handle the sub folders of deploy.skip.

[chingor13]

License header?

[suztomo]

Right now many checks are red. Let's not increase the checks in this repository.