code: func (rc *RulesCache) SetupConfigValidation(rules *validation.RuleSet) {
  	rules.Add("services/${appid}", serviceAccountsCfg, func(ctx *validation.Context, configSet, path string, content []byte) error {
  		cfg := &admin.ServiceAccountsPermissions{}
  		if err := proto.UnmarshalText(string(content), cfg); err != nil {
  			ctx.Errorf("not a valid ServiceAccountsPermissions proto message - %s", err)
  		} else {
  			validateServiceAccountsCfg(ctx, cfg)
  		}
  		return nil
  	})
  }
docs: // SetupConfigValidation registers the config validation rules.