Library generation failed (d9aa99c)

See [failed job](https://github.com/googleapis/google-cloudevents-java/actions/runs/17017108909)

Start with the linked failed GitHub Actions job for run 17017108909 and inspect the failing library-generation step and its logs. The issue provides no file or test entry point, so identify the affected generation process from the job output. Done means the library generation job completes successfully.

索引モデルが issue の本文から書いたものです。