code: func (pm *VolumePluginMgr) FindMapperPluginByName(name string) (BlockVolumePlugin, error) {
  	volumePlugin, err := pm.FindPluginByName(name)
  	if err != nil {
  		return nil, err
  	}
  
  	if blockVolumePlugin, ok := volumePlugin.(BlockVolumePlugin); ok {
  		return blockVolumePlugin, nil
  	}
  	return nil, nil
  }
docs: // FindMapperPluginByName fetches a block volume plugin by name.