@Test
@SuppressWarnings("null")
public void testIsAncestorOf() {

    assertThatThrownBy(() -> EMPTY.isAncestorOf(null)).isInstanceOf(NullPointerException.class);
    assertThat(EMPTY.isAncestorOf(EMPTY)).isFalse();
    assertThat(SECTOR_REGION.isAncestorOf(SECTOR_REGION)).isFalse();
    assertThat(SECTOR_REGION.isAncestorOf(INDUSTRY)).isTrue();
    assertThat(INDUSTRY.isAncestorOf(SECTOR_REGION)).isFalse();
}