private static class ConcreteIntegerString extends Fourth<Integer, String> {}

  private static class ConcreteStringInteger extends Fourth<String, Integer> {}

  public void testAssignableClassToClass() {
    @SuppressWarnings("rawtypes") // To test TypeToken<List>
    TypeToken<List> tokL = new TypeToken<List>() {};
    assertTrue(tokL.isSupertypeOf(List.class));