#vulnerable code 
                                public void testMapUnwrapDeserialize() throws Exception
    {
        MapUnwrap root = mapper.readValue("{\"map.test\": 6}", MapUnwrap.class);

        assertEquals(1, root.map.size());
        assertEquals(6, ((Number)root.map.get("test")).intValue());
    } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public void testMapUnwrapDeserialize() throws Exception
    {
        MapUnwrap root = MAPPER.readValue("{\"map.test\": 6}", MapUnwrap.class);

        assertEquals(1, root.map.size());
        assertEquals(6, ((Number)root.map.get("test")).intValue());
    }