@Override
    public boolean next(List<? super ExtendedCell> result, ScannerContext scannerContext)
      throws IOException {
      return scanner.next(result, scannerContext);
    }
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