#vulnerable code 
                                private String downloadNzb(SearchResultEntity result) throws IOException {
        Request request = new Request.Builder().url(result.getLink()).build();
        Indexer indexerByName = searchModuleProvider.getIndexerByName(result.getIndexer().getName());
        Integer timeout = indexerByName.getConfig().getTimeout().orElse(configProvider.getBaseConfig().getSearching().getTimeout());
        try (Response response = clientHttpRequestFactory.getOkHttpClientBuilder(request.url().uri()).readTimeout(timeout, TimeUnit.SECONDS).connectTimeout(timeout, TimeUnit.SECONDS).build().newCall(request).execute()) {
            return response.body().string();
        }
    } 
                            #location 6 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                private String downloadNzb(SearchResultEntity result) throws IOException {
        Request request = new Request.Builder().url(result.getLink()).build();
        Indexer indexerByName = searchModuleProvider.getIndexerByName(result.getIndexer().getName());
        Integer timeout = indexerByName.getConfig().getTimeout().orElse(configProvider.getBaseConfig().getSearching().getTimeout());
        try (Response response = clientHttpRequestFactory.getOkHttpClientBuilder(request.url().uri()).readTimeout(timeout, TimeUnit.SECONDS).connectTimeout(timeout, TimeUnit.SECONDS).build().newCall(request).execute()) {
            if (!response.isSuccessful()) {
                throw new IOException("Unsuccessful NZB download from URL " + result.getLink() + ". Message: " + response.message());
            }
            ResponseBody body = response.body();
            if (body == null || Strings.isNullOrEmpty(body.string())) {
                throw new IOException("NZB downloaded from " + result.getLink() + " is empty");
            }
            String content = body.string();
            return content;
        }
    }