default void postStartRegionOperation(ObserverContext<? extends RegionCoprocessorEnvironment> ctx,
    Operation operation) throws IOException {
  }
This will be called for region operations where read lock is acquired in
{@link Region#startRegionOperation()}.
@param operation The operation is about to be taken on the region
hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/RegionObserver.java