protected void setup() {
    // save current null values for later restoration
    saveDefaultDefaultNullValues = ConversionManager.getDefaultManager().getDefaultNullValues();
    saveDefaultNullValues =
        getSession().getLogin().getPlatform().getConversionManager().getDefaultNullValues();
    getSession()
        .getLogin()
        .getPlatform()
        .getConversionManager()
        .setDefaultNullValues(new Hashtable());
    getSession().getLogin().setDefaultNullValue(String.class, "null");
    getSession().getLogin().setDefaultNullValue(int.class, new Integer(-1));
    // Reinit mappings.
    for (DatabaseMapping mapping : getSession().getDescriptor(Address.class).getMappings()) {
      if (mapping.isDirectToFieldMapping()) {
        mapping.preInitialize(getAbstractSession());
      }
    }
    getAbstractSession().beginTransaction();

    employee = new Employee();
    employee.setFirstName("Fred");
    employee.setLastName("Flintstone");
    employee.setSalary(22);
    employee.setGender("Male");
    Address address = new Address();
    address.setCity(null);
    employee.setAddress(address);

    getAbstractSession().writeObject(employee);
    // force the salary to be NULL
    getSession()
        .executeNonSelectingCall(
            new SQLCall("update SALARY set SALARY = null where EMP_ID = " + employee.getId()));
  }
 public void test() {
   Address address = (Address) getSession().readObject(Address.class);
   for (int i = 0; i < stressLevel; i++) {
     getSession().readAllObjects(Address.class);
     getSession()
         .readObject(Address.class, new ExpressionBuilder().get("id").equal(address.getId()));
   }
 }