@Override
    public Map<Short, Map<Short, ContainerStorageStats>> getContainerStorageStats(long referenceTimeInMs,
        List<Short> accountIdsToExclude) throws StoreException {
      if (throwStoreException) {
        throw new StoreException("Test", StoreErrorCodes.UnknownError);
      }
      return containerStatsMap;
    }
Mocked {@link StoreStats} to return predefined map when getContainerStorageStats is called.
ambry-server/src/test/java/com/github/ambry/server/StatsManagerTest.java