default Container getContainerById(short accountId, Short containerId) throws AccountServiceException {
    Account account = getAccountById(accountId);
    return account != null ? account.getContainerById(containerId) : null;
  }
Get an existing container from a given account.
@param accountId the name of account which container belongs to.
@param containerId the id of container to get.
@return the requested {@link Container} object or null if not present.
@throws AccountServiceException if exception occurs when getting container.
ambry-api/src/main/java/com/github/ambry/account/AccountService.java