#fixed code
                                @Test
    public void testIdFieldAnnotated() throws Exception {
        IdFieldAnnotated o = new IdFieldAnnotated();
        o.id = "blah";
        JacksonDBCollection<IdFieldAnnotated, String> coll = createCollFor(o, String.class);
        coll.insert(o);
        IdFieldAnnotated result = coll.findOneById("blah");
        assertThat(result, notNullValue());
        assertThat(result.id, equalTo("blah"));
    }
#vulnerable code 
                                @Test
    public void testIdFieldAnnotated() throws Exception {
        IdFieldAnnotated o = new IdFieldAnnotated();
        o.id = "blah";
        JacksonDBCollection<IdFieldAnnotated, String> coll = createCollFor(o, String.class);
        WriteResult<IdFieldAnnotated, String> writeResult = coll.insert(o);
        assertThat(writeResult.getSavedId(), equalTo("blah"));
        assertThat(writeResult.getDbObject().get("id"), nullValue());
        IdFieldAnnotated result = coll.findOneById("blah");
        assertThat(result, notNullValue());
        assertThat(result.id, equalTo("blah"));
    } 
                            #location 11 
                            #vulnerability type NULL_DEREFERENCE