private long getCounterValue(Map<String, Counter> counters, String className, String suffix) {
    return counters.get(className + "." + suffix).getCount();
  }
Get the counter value for the metric in {@link StorageManagerMetrics} for the given class and suffix.
@param counters Map of counter metrics to use
@param className the class to which the metric belongs to
@param suffix the suffix of the metric that distinguishes it from other metrics in the class.
@return the value of the counter.
ambry-store/src/test/java/com/github/ambry/store/StorageManagerTest.java