@Override
  public boolean preScannerNext(final ObserverContext<? extends RegionCoprocessorEnvironment> c,
    final InternalScanner s, final List<Result> result, final int limit, final boolean hasNext)
    throws IOException {
    requireScannerOwner(s);
    return hasNext;
  }
Checks whether cell contains any tag with type as VISIBILITY_TAG_TYPE. This tag type is
reserved and should not be explicitly set by user.
@param cell The cell under consideration
@param pair An optional pair of type {@code <Boolean, Tag>} which would be reused if already
            set and new one will be created if NULL is passed
@return If the boolean is false then it indicates that the cell has a RESERVERD_VIS_TAG and
        with boolean as true, not null tag indicates that a string modified tag was found.
hbase-server/src/main/java/org/apache/hadoop/hbase/security/visibility/VisibilityController.java