@Override
 public void applyPromotion(final Owner owner, final Bonus bonus) {
   final Account account = accountService.findAccountByOwner(owner);
   Assert.state(account != null, "account doesn't exist");
   final double updatedBalance = account.getBalance() + bonus.getBonusAmount();
   accountService.updateAccountBalance(account, updatedBalance);
 }
 @Override
 public Collection<Account> findRichPeople() {
   return accountService.findAccountsWithBalanceGreaterThan(MILLION);
 }