#vulnerable code 
                              public Result<com.belerweb.social.weibo.bean.User> domainShow(String source, String accessToken,
      String domain) {
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    weibo.addNotNullParameter(params, "source", source);
    weibo.addNotNullParameter(params, "access_token", accessToken);
    weibo.addParameter(params, "domain", domain);
    String json = weibo.post("https://api.weibo.com/2/users/domain_show.json", params);
    return Result.perse(json, com.belerweb.social.weibo.bean.User.class);
  } 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              public Result<com.belerweb.social.weibo.bean.User> domainShow(String source, String accessToken,
      String domain) {
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    weibo.addNotNullParameter(params, "source", source);
    weibo.addNotNullParameter(params, "access_token", accessToken);
    weibo.addParameter(params, "domain", domain);
    String json = weibo.post("https://api.weibo.com/2/users/domain_show.json", params);
    return Result.parse(json, com.belerweb.social.weibo.bean.User.class);
  }