@Test
  public void isStockServicesASingleton() {

    logger.info("Start  isStockServicesASingleton ...");

    SimpleStockServicesFactory factoryInstance = SimpleStockServicesFactory.INSTANCE;

    SimpleStockService simpleStockServiceA = factoryInstance.getSimpleStockService();
    SimpleStockService simpleStockServiceB = factoryInstance.getSimpleStockService();

    Assert.assertNotNull(simpleStockServiceA);
    Assert.assertNotNull(simpleStockServiceB);

    Assert.assertTrue(simpleStockServiceA.equals(simpleStockServiceB));

    logger.info("Finish isStockServicesASingleton ...OK");
  }