Warn about the lack of access controls for SD card HTTP caches.

 * the hit rate, but it may also just waste filesystem space!

 *

 * <p>For some applications it may be preferable to create the cache in the

 * external storage directory. Although it often has more free space, external

 * storage is optional and—even if available—can disappear during

 * use. Retrieve the external cache directory using {@link Context#getExternalCacheDir()}. If this method

 * returns null, your application should fall back to either not caching or

 * caching on non-external storage. If the external storage is removed during

 * use, the cache hit rate will drop to zero and ongoing cache reads will fail.

 * external storage directory. <strong>There are no access controls on the

 * external storage directory so it should not be used for caches that could

 * contain private data.</strong> Although it often has more free space,

 * external storage is optional and—even if available—can disappear

 * during use. Retrieve the external cache directory using {@link

 * Context#getExternalCacheDir()}. If this method returns null, your application

 * should fall back to either not caching or caching on non-external storage. If

 * the external storage is removed during use, the cache hit rate will drop to

 * zero and ongoing cache reads will fail.

 *

 * <p>Flushing the cache forces its data to the filesystem. This ensures that

 * all responses written to the cache will be readable the next time the

     */

    public void flush() {

        try {

            delegate.getCache().flush(); // TODO: fix flush() to not throw?

            delegate.getCache().flush();

        } catch (IOException ignored) {

        }

    }