@Override
    public void preScannerOpen(ObserverContext<? extends RegionCoprocessorEnvironment> c, Scan scan)
      throws IOException {
      scan.setFilter(new NoDataFilter());
    }
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