@Test
public void testToUpperList() {

    List<String> sourceList = null;
    Assertions.assertNull(CollectionUtils.toUpperList(sourceList));
    sourceList = new ArrayList<>();
    Assertions.assertEquals(Collections.EMPTY_LIST, CollectionUtils.toUpperList(sourceList));
    List<String> anotherList = new ArrayList<>();
    sourceList.add("a");
    anotherList.add("A");
    sourceList.add("b");
    anotherList.add("b");
    sourceList.add("c");
    anotherList.add("C");
    Assertions.assertEquals(CollectionUtils.toUpperList(sourceList), CollectionUtils.toUpperList(anotherList));
    anotherList.add("D");
    Assertions.assertTrue(
        CollectionUtils.toUpperList(anotherList).containsAll(CollectionUtils.toUpperList(sourceList)));
}