code: @Override
      public double getLoadExceptionRate() {
          long totalLoadCount = loadSuccessCount.get() + loadExceptionCount.get();
          return (totalLoadCount == 0) ? 0.0 : (double) loadExceptionCount.get() / totalLoadCount;
      }
docs: Returns the ratio of cache loading attempts which threw exceptions. This is defined as {@code
  loadExceptionCount / (loadSuccessCount + loadExceptionCount)}, or {@code 0.0} when {@code
  loadSuccessCount + loadExceptionCount == 0}.