#vulnerable code 
                                private OkHttpConnector connector(String apiUrl) {
        Jenkins jenkins = GitHubWebHook.getJenkinsInstance();
        OkHttpClient client = new OkHttpClient().setProxy(getProxy(apiUrl));

        if (configuration().getClientCacheSize() > 0) {
            File cacheDir = new File(jenkins.getRootDir(), GitHubPlugin.class.getName() + ".cache");
            Cache cache = new Cache(cacheDir, configuration().getClientCacheSize() * 1024 * 1024);
            client.setCache(cache);
        }

        return new OkHttpConnector(new OkUrlFactory(client));
    } 
                            #location 6 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                private OkHttpConnector connector(String apiUrl) {
        OkHttpClient client = new OkHttpClient().setProxy(getProxy(apiUrl));

        if (configuration().getClientCacheSize() > 0) {
            File cacheDir = getCacheBaseDirFor(GitHubWebHook.getJenkinsInstance());
            Cache cache = new Cache(cacheDir, configuration().getClientCacheSize() * 1024 * 1024);
            client.setCache(cache);
        }

        return new OkHttpConnector(new OkUrlFactory(client));
    }