code: @Override
    public ImageInputStream getImageInputStream(long txid) throws IOException {
      URLImageInputStream stream = loggers.getImageInputStream(txid,
          httpConnectReadTimeoutMs);
      if (stream == null) {
        throw new IOException("Cannot obtain input stream for image: " + txid);
      }
      return new ImageInputStream(txid, stream, stream.getImageDigest(),
          stream.toString(), stream.getSize());
    }
docs: Get input stream to one of the nodes for given txid.