code: public byte[] readBlob(String key) throws IOException, KeyNotFoundException{
          ByteArrayOutputStream out = new ByteArrayOutputStream();
          readBlobTo(key, out);
          byte[] bytes = out.toByteArray();
          out.close();
          return bytes;
      }
docs: Wrapper around readBlobTo which
  returns a ByteArray output stream.
  @param key  Key for the blob.
  the read privilege for the blob.
  @return ByteArrayOutputStream
  @throws IOException
  @throws KeyNotFoundException