public InputStream streamFile(
      DownloadableFile downloadableFile, UUID jobId, TemporaryPerJobDataStore jobStore)
      throws IOException {
    checkState(downloadableFile.getFetchableUrl() != null, "missing fetchable URL for file");
    if (downloadableFile.isInTempStore()) {
      return jobStore.getStream(jobId, downloadableFile.getFetchableUrl()).getStream();
    } else {
      return this.remoteFileStreamer.get(downloadableFile);
    }
  }
Streams a file from wherever it lives, making no attempt to tee into jobStore.
portability-spi-api/src/main/java/org/datatransferproject/spi/api/transport/JobFileStream.java