#vulnerable code 
                              public Result<UserCounts> counts(String source, String accessToken, List<String> uids) {
    if (uids == null || uids.size() > 100) {
      throw new SocialException("需要获取数据的用户UID，必须且最多不超过100个");
    }

    List<NameValuePair> params = new ArrayList<NameValuePair>();
    weibo.addNotNullParameter(params, "source", source);
    weibo.addNotNullParameter(params, "access_token", accessToken);
    weibo.addParameter(params, "uids", StringUtils.join(uids, ","));
    String result = weibo.post("https://api.weibo.com/2/users/domain_show.json", params);
    return Result.perse(result, UserCounts.class);
  } 
                            #location 11 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              public Result<UserCounts> counts(String source, String accessToken, List<String> uids) {
    if (uids == null || uids.size() > 100) {
      throw new SocialException("需要获取数据的用户UID，必须且最多不超过100个");
    }

    List<NameValuePair> params = new ArrayList<NameValuePair>();
    weibo.addNotNullParameter(params, "source", source);
    weibo.addNotNullParameter(params, "access_token", accessToken);
    weibo.addParameter(params, "uids", StringUtils.join(uids, ","));
    String result = weibo.post("https://api.weibo.com/2/users/domain_show.json", params);
    return Result.parse(result, UserCounts.class);
  }