code: func All(settings environment.EnvSettings) Providers {
  	result := Providers{
  		{
  			Schemes: []string{"http", "https"},
  			New:     newHTTPGetter,
  		},
  	}
  	pluginDownloaders, _ := collectPlugins(settings)
  	result = append(result, pluginDownloaders...)
  	return result
  }
docs: // All finds all of the registered getters as a list of Provider instances.
  // Currently the build-in http/https getter and the discovered
  // plugins with downloader notations are collected.