docs: @BetaApi
    public final Operation deleteSignedUrlKeyBackendBucket(
        ProjectGlobalBackendBucketName backendBucket, String keyName) {
  
      DeleteSignedUrlKeyBackendBucketHttpRequest request =
          DeleteSignedUrlKeyBackendBucketHttpRequest.newBuilder()
              .setBackendBucket(backendBucket == null ? null : backendBucket.toString())
              .setKeyName(keyName)
              .build();
      return deleteSignedUrlKeyBackendBucket(request);
    }