@Override
  public InputStream get(DownloadableItem downloadableItem) throws IOException {
    checkState(
        downloadableItem.getFetchableUrl() != null,
        "trying to download incomplete DownloadableItem: missing fetchable URL");
    checkState(
        !downloadableItem.isInTempStore(),
        "trying to re-download an already stored item: \"%s\"",
        downloadableItem.getFetchableUrl());

    return get(downloadableItem.getFetchableUrl());
  }
Implements a simple HTTP GET against a URL to stream the results.
portability-spi-api/src/main/java/org/datatransferproject/spi/api/transport/UrlGetStreamer.java