#vulnerable code 
                              public void run(final PojoClass pojoClass) {
    IdentityFactory.registerIdentityHandler(identityHandlerStub);

    firstPojoClassInstance = ValidationHelper.getMostCompleteInstance(pojoClass);
    secondPojoClassInstance = ValidationHelper.getMostCompleteInstance(pojoClass);

    // check one way
    identityHandlerStub.areEqualReturn = RandomFactory.getRandomValue(Boolean.class);
    checkEquality();

    identityHandlerStub.areEqualReturn = !identityHandlerStub.areEqualReturn;
    checkEquality();

    identityHandlerStub.doGenerateReturn = RandomFactory.getRandomValue(Integer.class);
    checkHashCode();

    identityHandlerStub.doGenerateReturn = RandomFactory.getRandomValue(Integer.class);
    checkHashCode();

    IdentityFactory.unregisterIdentityHandler(identityHandlerStub);
  } 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              public void run(final PojoClass pojoClass) {
    Object instance1 = ValidationHelper.getMostCompleteInstance(pojoClass);
    Object instance2 = ValidationHelper.getMostCompleteInstance(pojoClass);

    IdentityHandlerStub identityHandlerStub = new IdentityHandlerStub(instance1, instance2);
    IdentityFactory.registerIdentityHandler(identityHandlerStub);

    // check one way
    identityHandlerStub.areEqualReturn = RandomFactory.getRandomValue(Boolean.class);
    checkEquality(instance1, instance2, identityHandlerStub);

    identityHandlerStub.areEqualReturn = !identityHandlerStub.areEqualReturn;
    checkEquality(instance1, instance2, identityHandlerStub);

    identityHandlerStub.doGenerateReturn = RandomFactory.getRandomValue(Integer.class);
    checkHashCode(instance1, identityHandlerStub);

    identityHandlerStub.doGenerateReturn = RandomFactory.getRandomValue(Integer.class);
    checkHashCode(instance1, identityHandlerStub);

    IdentityFactory.unregisterIdentityHandler(identityHandlerStub);
  }