code: protected Counter findCounter(String counterName, String displayName) {
      Counter result = counters.get(counterName);
      if (result == null) {
        result = new Counter(counterName, displayName);
        counters.put(counterName, result);
      }
      return result;
    }
docs: Internal to find a counter in a group.
  @param counterName the name of the counter
  @param displayName the display name of the counter
  @return the counter that was found or added