@Test
public void encodeMap() {

    Map<String, String> map = null;
    Assertions.assertNull(CollectionUtils.encodeMap(map));
    map = new HashMap<>();
    Assertions.assertEquals("", CollectionUtils.encodeMap(map));
    map.put("x", "1");
    Assertions.assertEquals("x=1", CollectionUtils.encodeMap(map));
    map.put("y", "2");
    Assertions.assertEquals("x=1&y=2", CollectionUtils.encodeMap(map));
}