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;
  
              // This example creates a new account and attempts to save it without an identifier.
              Account account2 = new Account();
              persistenceManager.saveEntity(account2);
  
              // The account ID was not auto incremented.
              // This is because we removed the generator from the @Identifier annotation.
              assert 0 == account2.getAccountId();
          } catch (OnyxException e)
          {
              e.printStackTrace();
          }
      }
docs: Main Method to demo the functionality
  @param persistenceManager Open and valid persistence manager