@Override
    public int size() {
        return map.size();
    }
@Test
    public void testSize() {
        ExtendedSet<TestValue> nonemptyset = new ExtendedSet<>(Maps.newConcurrentMap());
        TestValue val = new TestValue("foo", 1);
        assertTrue(nonemptyset.add(val));
        assertTrue(nonemptyset.contains(val));
        assertEquals(1, nonemptyset.size());
        TestValue secval = new TestValue("goo", 2);
        assertTrue(nonemptyset.add(secval));
        assertTrue(nonemptyset.contains(secval));
        assertEquals(2, nonemptyset.size());

        ExtendedSet<TestValue> emptyset = new ExtendedSet<>(Maps.newConcurrentMap());
        assertEquals(0, emptyset.size());
    }