private Map<String, Map<String, Long>> cloneMap(Map<String, Map<String, Long>> origin) {
    if (origin == null) {
      return null;
    }
    Map<String, Map<String, Long>> clone = new HashMap<>();
    origin.entrySet().forEach(ent -> clone.put(ent.getKey(), new HashMap<>(ent.getValue())));
    return clone;
  }
Test to update container storage usage monthly base.
ambry-quota/src/integration-test/java/com/github/ambry/quota/storage/MySqlStorageUsageRefresherTest.java