Library generation failed (3b86441)

See [failed job](https://github.com/googleapis/google-cloudevents-java/actions/runs/17665252542)

Open the linked GitHub Actions job and inspect the failed library-generation step and its logs. Identify the generation command or entry point reported there, then reproduce the failure locally if the job provides enough detail. Done means the generation job completes successfully and the library output is produced.

索引モデルが issue の本文から書いたものです。