code: static void demo(PersistenceManager persistenceManager)
      {
  
          try {
              // Fetch an account.  Notice that the id is now a long rather than an integer.
              Account account = persistenceManager.findById(Account.class, 1L);
              assert account != null;
              assert account.getAccountId() == 1L;
  
              // The Account Name is a new field and is now persistable.
              // This demonstrates that we can now take
              // advantage of the new field.
              account.setAccountName("Utility Bill");
              persistenceManager.saveEntity(account);
  
              // Verify it was indeed persisted
              account = persistenceManager.findById(Account.class, 1L);
              assert account != null;
              assert account.getAccountName().equals("Utility Bill");
  
              // Notice, the one thing that we cannot demonstrate is that we removed a field, "balanceDue"
              // Don't worry, we can add it back and the data will still be there since it has not been orphaned.
          } catch (OnyxException e)
          {
              e.printStackTrace();
              assert false;
          }
      }
docs: Main Method to demo the functionality
  @param persistenceManager Open and valid persistence manager