### Question:
Stack implements com.iabtcf.extras.gvl.Stack { @Override public List<Integer> getSpecialFeatures() { return specialFeatures; }  @Override int getId(); @Override List<Integer> getSpecialFeatures(); @Override List<Integer> getPurposes(); @Override String getName(); @Override String getDescription();  }### Answer:
@Test public void testGetSpecialFeatures() { Assert.assertNotNull(stackTwenty.getSpecialFeatures()); Assert.assertEquals(0, stackTwenty.getSpecialFeatures().size()); }