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