code: func (b *downwardAPIVolumeMounter) SetUp(fsGroup *int64) error {
  	return b.SetUpAt(b.GetPath(), fsGroup)
  }
docs: // SetUp puts in place the volume plugin.
  // This function is not idempotent by design. We want the data to be refreshed periodically.
  // The internal sync interval of kubelet will drive the refresh of data.
  // TODO: Add volume specific ticker and refresh loop