@Override
    public Optional<RegionObserver> getRegionObserver() {
      return Optional.of(this);
    }
Verifies that if a coproc returns an InternalScanner which implements Shipper, the shippped
method is appropriately called in Compactor.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestCompactionWithShippingCoprocessor.java