code: private static void seedData(PersistenceManager manager) throws OnyxException
      {
          Account account = new Account();
          //noinspection SpellCheckingInspection
          account.setAccountName("Timbob's Lawn Care");
          account.setBalanceDue(55.43f);
  
          Invoice marchLawnInvoice = new Invoice();
          marchLawnInvoice.setDueDate(parseDate("04-01-2016"));
          marchLawnInvoice.setInvoiceDate(parseDate("03-01-2016"));
          marchLawnInvoice.setNotes("Why did we need to mow your lawn.  Its basically a dirt field.");
          marchLawnInvoice.setInvoiceId(1L);
          marchLawnInvoice.setAmount(44.32);
          marchLawnInvoice.setAccount(account);
  
          Invoice aprilLawnInvoice = new Invoice();
          aprilLawnInvoice.setDueDate(parseDate("04-01-2016"));
          aprilLawnInvoice.setInvoiceDate(parseDate("03-01-2016"));
          aprilLawnInvoice.setNotes("Its April, your lawn should be growing by now.");
          aprilLawnInvoice.setInvoiceId(2L);
          aprilLawnInvoice.setAmount(44.32);
          aprilLawnInvoice.setAccount(account);
  
          manager.saveEntity(account);
          manager.saveEntity(marchLawnInvoice);
          manager.saveEntity(aprilLawnInvoice);
  
          Payment marchLawnCarePayment = new Payment();
          marchLawnCarePayment.setPaymentId(1L);
          marchLawnCarePayment.setInvoice(marchLawnInvoice);
          marchLawnCarePayment.setAmount(44.32);
  
          manager.saveEntity(marchLawnCarePayment);
  
          Account account1 = manager.findById(Account.class, 1);
          assert account1 != null;
          assert account1.getAccountId() == 1L;
      }
docs: Fill the database with some test data, so that we can show how the data model updates impact the changes to the values.
  
  @param manager Persistence Manager used to save the entities
  @throws OnyxException Failure to persist entities