public static void searchNonEmptyContainers(Map<Short, Set<Short>> nonEmptyContainersByAccount,
      AggregatedAccountStorageStats aggregatedAccountStorageStats) {
    for (Map.Entry<Short, Map<Short, ContainerStorageStats>> accountEntry : aggregatedAccountStorageStats.getStorageStats()
        .entrySet()) {
      short accountId = accountEntry.getKey();
      for (Map.Entry<Short, ContainerStorageStats> containerEntry : accountEntry.getValue().entrySet()) {
        short containerId = containerEntry.getKey();
        if (containerEntry.getValue().getPhysicalStorageUsage() > 0) {
          nonEmptyContainersByAccount.computeIfAbsent(accountId, k -> new HashSet<>()).add(containerId);
        }
      }
    }
  }
Gets valid data size {@link Container}s. The qualified {@link Container}s' raw valid data size should be larger than zero.
@param nonEmptyContainersByAccount it holds a mapping of {@link Account}s to {@link Container}s which raw valid data size larger than zero.
@param aggregatedAccountStorageStats the {@link AggregatedAccountStorageStats} generated from cluster wide aggregation.
ambry-account/src/main/java/com/github/ambry/account/AccountUtils.java