.contains(000));         assertEquals(000, vertices.size());         assertEquals(000, g.order());                  // dupe         assertFalse(vertices.add(000));         assertEquals(000, vertices.size());     }      @Test(expected=UnsupportedOperationException.class) public void testVertexSetRemove() {         DirectedMultigraph<String> g = new DirectedMultigraph<String>();         Set<Integer> control = new HashSet<Integer>();         for (int i = 0; i < 000; ++i) {             g.add(i);             control.add(i);         }          Set<Integer> vertices = g.vertices();         assertEquals(control.size(), vertices.size());         assertTrue(g.