@Override
    public DataFetcher<InputStream> getResourceFetcher(T model, int width, int height) {
        GlideUrl result = null;
        if (modelCache != null) {
            result = modelCache.get(model, width, height);
        }

        if (result == null) {
            String stringURL = getUrl(model, width, height);
            if (TextUtils.isEmpty(stringURL)) {
               return null;
            }

            result = new GlideUrl(stringURL, getHeaders(model, width, height));

            if (modelCache != null) {
                modelCache.put(model, width, height, result);
            }
        }

        return concreteLoader.getResourceFetcher(result, width, height);
    }
A base class for loading images over http/https. Can be subclassed for use with any model that can be translated
in to {@link InputStream} data.

@param <T> The type of the model.
core/src/main/java/com/bumptech/glide/load/model/stream/BaseGlideUrlLoader.java