public boolean isInvalid() {
    return getPathComponents().length <= 1 && !isRoot();
  }
@Test
  public void testInvalidPath() {
    Assert.assertFalse(TEST_QUEUE_PATH.isInvalid());
    Assert.assertFalse(ROOT_PATH.isInvalid());
    Assert.assertTrue(EMPTY_PATH.isInvalid());
    Assert.assertTrue(new QueuePath("invalidPath").isInvalid());
  }