@Override
  public Container getContainerByName(String accountName, String containerName) throws AccountServiceException {
    return cachedAccountService.getContainerByNameHelper(accountName, containerName);
  }
Gets the {@link Container} by its name and parent {@link Account} name by looking up in in-memory cache.
If it is not present in in-memory cache, it queries from mysql db and updates the cache.
@param accountName the name of account which container belongs to.
@param containerName the name of container to get.
@return {@link Container} if found in cache or mysql db. Else, returns {@code null}.
@throws AccountServiceException
ambry-account/src/main/java/com/github/ambry/account/MySqlAccountService.java