code: func (p DummyPlugin) Backup(endpoint plugin.ShieldEndpoint) error {
  	data, err := endpoint.StringValue("data")
  	if err != nil {
  		return err
  	}
  
  	return plugin.Exec(fmt.Sprintf("/bin/echo %s", data), plugin.STDOUT)
  }
docs: // Called when you want to back data up. Examine the ShieldEndpoint passed in, and perform actions accordingly