code: @Test public void testMapEquals() throws Exception {
    assertTrue(CollectionUtils.mapEquals(null,null));
    assertFalse(CollectionUtils.mapEquals(null,new HashMap<String,String>()));
    assertFalse(CollectionUtils.mapEquals(new HashMap<String,String>(),null));
    assertTrue(CollectionUtils.mapEquals(CollectionUtils.toStringMap("1","a","2","b"),CollectionUtils.toStringMap("1","a","2","b")));
    assertFalse(CollectionUtils.mapEquals(CollectionUtils.toStringMap("1","a"),CollectionUtils.toStringMap("1","a","2","b")));
  }
  