Iterator<String> iterator() {
        if (serverUrls.isEmpty()) {
            LOGGER.error("[{}] [iterator-serverlist] No server address defined!", name);
        }
        return new ServerAddressIterator(serverUrls);
    }
@Test
    void testIterator() {
        List<String> addrs = new ArrayList<>();
        String addr = "1.1.1.1:8848";
        addrs.add(addr);
        final ServerListManager mgr = new ServerListManager(addrs, "aaa");
        
        // new iterator
        final Iterator<String> it = mgr.iterator();
        assertTrue(it.hasNext());
        assertEquals(addr, it.next());
        
        assertNull(mgr.getIterator());
        mgr.refreshCurrentServerAddr();
        assertNotNull(mgr.getIterator());
        
        final String currentServerAddr = mgr.getCurrentServerAddr();
        assertEquals(addr, currentServerAddr);
        
        final String nextServerAddr = mgr.getNextServerAddr();
        assertEquals(addr, nextServerAddr);
        
        final Iterator<String> iterator1 = mgr.iterator();
        assertTrue(iterator1.hasNext());
        
    }