@Override
  public boolean postScannerFilterRow(
    final ObserverContext<? extends RegionCoprocessorEnvironment> e, final InternalScanner s,
    final Cell currentRow, final boolean hasMore) throws IOException {
    ctPostScannerFilterRow.incrementAndGet();
    return hasMore;
  }
A sample region observer that tests the RegionObserver interface. It works with
TestRegionObserverInterface to provide the test case.
hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/SimpleRegionObserver.java