code: func filterAuthorizedBuilders(c context.Context, builders []string) ([]string, error) {
  	buckets := stringset.New(0)
  	for _, b := range builders {
  		id := buildsource.BuilderID(b)
  		buildType, bucket, _, err := id.Split()
  		if err != nil {
  			logging.Warningf(c, "found malformed builder ID %q", id)
  			continue
  		}
  		if buildType == "buildbucket" {
  			buckets.Add(bucket)
  		}
  	}
  	perms, err := common.BucketPermissions(c, buckets.ToSlice()...)
  	if err != nil {
  		return nil, err
  	}
  	okBuilders := make([]string, 0, len(builders))
  	for _, b := range builders {
  		id := buildsource.BuilderID(b)
  		buildType, bucket, _, err := id.Split()
  		if err != nil {
  			continue
  		}
  		if buildType != "buildbucket" || perms.Can(bucket, access.AccessBucket) {
  			okBuilders = append(okBuilders, b)
  		}
  	}
  	return okBuilders, nil
  }
docs: // filterAuthorizedBuilders filters out builders that the user does not have access to.