// check retainable properties
List<Class<? extends CategoryProperty>> retainableProps = params
.getRetainableProperties();
assertNull("Unexpected content in retainable list", retainableProps);
params.addCategoryEnhancements(new CategoryEnhancementDummy2());
List<CategoryEnhancement> enhancements = params
.getCategoryEnhancements();
assertEquals("Wrong number of enhancements", 2, enhancements.size());