code: func init() {
  	validation.Rules.Add(
  		"regex:projects/.*",
  		"${appid}.cfg",
  		func(ctx *validation.Context, configSet, path string, content []byte) error {
  			cfg := &notifypb.ProjectConfig{}
  			if err := proto.UnmarshalText(string(content), cfg); err != nil {
  				ctx.Errorf("invalid ProjectConfig proto message: %s", err)
  			} else {
  				validateProjectConfig(ctx, cfg)
  			}
  			return nil
  		})
  
  	validation.Rules.Add(
  		"regex:projects/.*",
  		`regex:${appid}/email-templates/[^/]+\.template`,
  		validateEmailTemplateFile)
  }
docs: // init registers validators for the project config and email template files.