final Properties props = new Properties();
      props.put("hibernate.connection.shutdown", "true");
      props.put("hibernate.connection.driver_class", "org.hsqldb.jdbcDriver");
      props.put("hibernate.dialect", "org.hibernate.dialect.H2Dialect");
      props.put("hibernate.hbm2ddl.auto", "create-drop");
      props.put("hibernate.current_session_context_class",
            "org.springframework.orm.hibernate4.SpringSessionContext");
      props.put("hibernate.show_sql", "true");

      final DatasourceConnectionProviderImpl service = new DatasourceConnectionProviderImpl();
      service.setDataSource(new SingleConnectionDataSource("jdbc:hsqldb:mem:test", "sa", "", true));
      service.configure(props);
      final ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().addService(
            ConnectionProvider.class, service).applySettings(props).buildServiceRegistry();

      final MetadataSources metadataSources = new MetadataSources(serviceRegistry);
      metadataSources.addResource("myPackage/ObjectToTest.hbm.xml");
      final Metadata metadata = metadataSources.buildMetadata();
      sessionFactory = metadata.buildSessionFactory();

   @org.junit.Test
   public void testPersist() {

      new TransactionTemplate(new HibernateTransactionManager(sessionFactory)).execute(new TransactionCallbackWithoutResult() {

         @Override
         protected void doInTransactionWithoutResult(final TransactionStatus status) {
            final Session currentSession = sessionFactory.getCurrentSession();
            final ObjectToTest object = new ObjectToTest("myText");
            currentSession.persist(object);
         }
      });

   }

<?xml version="1.0" encoding="ISO-8859-1"?>


<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping default-lazy="false"
   xmlns="http://www.hibernate.org/xsd/hibernate-mapping"
   xsi:schemaLocation="http://www.hibernate.org/xsd/hibernate-mapping hibernate-mapping-4.0.xsd"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

   <class name="myPackage.ObjectToTest">
      <id name="id">
         <generator class="native" />
      </id>
      <property name="text" />
   </class>

</hibernate-mapping>

Caused by: java.sql.SQLIntegrityConstraintViolationException: integrity constraint violation: NOT NULL check constraint; SYS_CT_10025 table: "ObjectToTest" column: "id"
   at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
   at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
   at org.hsqldb.jdbc.JDBCPreparedStatement.fetchResult(Unknown Source)
   at org.hsqldb.jdbc.JDBCPreparedStatement.executeUpdate(Unknown Source)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)