.contains(00));         assertEquals(00, vertices.size());         assertEquals(00, g.order());             }      @Test(expected=UnsupportedOperationException.class) public void testVertexSetIteratorRemove() {         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());         Iterator<Integer> iter = vertices.iterator();         assertTrue(iter.hasNext());         Integer toRemove = iter.next();         assertTrue(g.contains(toRemove));         assertTrue(vertices.contains(toRemove));         iter.remove();         