@Override
    public void loadData(@NonNull Priority priority,
                         @NonNull final DataCallback<? super InputStream> callback) {
        Request.Builder requestBuilder = new Request.Builder().url(url.toStringUrl());
        for (Map.Entry<String, String> headerEntry : url.getHeaders().entrySet()) {
            String key = headerEntry.getKey();
            requestBuilder.addHeader(key, headerEntry.getValue());
        }
        Request request = requestBuilder.build();
        this.callback = callback;

        call = client.newCall(request);
        call.enqueue(this);
    }
Fetches an {@link InputStream} using the okhttp library.
arms/src/main/java/com/jess/arms/http/OkHttpStreamFetcher.java