@Test
  public void testClassNamesToString() {
    List ifcs = new LinkedList();
    ifcs.add(Serializable.class);
    ifcs.add(Runnable.class);
    assertEquals("[interface java.io.Serializable, interface java.lang.Runnable]", ifcs.toString());
    assertEquals("[java.io.Serializable, java.lang.Runnable]", ClassUtils.classNamesToString(ifcs));

    List classes = new LinkedList();
    classes.add(LinkedList.class);
    classes.add(Integer.class);
    assertEquals("[class java.util.LinkedList, class java.lang.Integer]", classes.toString());
    assertEquals(
        "[java.util.LinkedList, java.lang.Integer]", ClassUtils.classNamesToString(classes));

    assertEquals("[interface java.util.List]", Collections.singletonList(List.class).toString());
    assertEquals("[java.util.List]", ClassUtils.classNamesToString(List.class));

    assertEquals("[]", Collections.EMPTY_LIST.toString());
    assertEquals("[]", ClassUtils.classNamesToString(Collections.EMPTY_LIST));
  }