#vulnerable code 
                              @Test
  public void canConvertLongs() throws IOException {
    List<Long> longs = Arrays.asList(Long.MAX_VALUE, Long.MIN_VALUE);
    for (Long original : longs) {
      String jsonString = JsonMapper.serializeJsonValue(original);
      long converted = (Long) JsonMapper.parseJsonValue(jsonString);
      assertEquals((long) original, converted);
    }
  } 
                            #location 6 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              @Test
  public void canConvertLongs() throws IOException {
    List<Long> longs = Arrays.asList(Long.MAX_VALUE, Long.MIN_VALUE);
    for (Long original : longs) {
      String jsonString = JsonMapper.serializeJson(original);
      long converted = (Long) JsonMapper.parseJsonValue(jsonString);
      assertEquals((long) original, converted);
    }
  }