@Override
  public void reset() {
    super.reset();
    // clear only here
    visibilityTagsDeleteColumns = null;
    visibilityTagsDeleteFamily = null;
    visibilityTagsDeleteFamilyVersion = null;
    visiblityTagsDeleteColumnVersion = null;
  }
This tag is used for the DELETE cell which has no visibility label.
hbase-server/src/main/java/org/apache/hadoop/hbase/security/visibility/VisibilityScanDeleteTracker.java