@Override
  public boolean filterRowKey(Cell cell) throws IOException {
    // Impl in FilterBase might do unnecessary copy for Off heap backed Cells.
    return false;
  }
This Filter checks the visibility expression with each KV against visibility labels associated
with the scan. Based on the check the KV is included in the scan result or gets filtered out.
hbase-server/src/main/java/org/apache/hadoop/hbase/security/visibility/VisibilityLabelFilter.java