@Override
    public void preGetOp(ObserverContext<? extends RegionCoprocessorEnvironment> c, Get get,
      List<Cell> result) throws IOException {
      c.bypass();
    }
Don't return any data from a scan by creating a custom {@link StoreScanner}.
hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/TestRegionObserverScannerOpenHook.java