@Override
    public void preGetOp(ObserverContext<? extends RegionCoprocessorEnvironment> e, Get get,
      List<Cell> results) throws IOException {
      preGetCounter.increment();
    }
RegionObserver that has a Counter for preGet()
hbase-server/src/test/java/org/apache/hadoop/hbase/coprocessor/TestCoprocessorMetrics.java