code: func validateServiceCfg(ctx *validation.Context, configSet, path string, content []byte) error {
  	settings := config.Settings{}
  	if err := protoutil.UnmarshalTextML(string(content), &settings); err != nil {
  		ctx.Error(err)
  	}
  	gitacls.ValidateConfig(ctx, settings.SourceAcls)
  	return nil
  }
docs: // validateServiceCfg implements validation.Func by taking a potential Milo
  // service global config, validating it, and writing the result into ctx.
  //
  // The validation we do include:
  //
  // * Make sure the config is able to be unmarshalled.