code: public static ByteSink asCompressedByteSink(File f) throws IOException {
      return GZIPByteSink.gzipCompress(Files.asByteSink(f));
    }
docs: Just like {@link Files#asByteSink(java.io.File, com.google.common.io.FileWriteMode...)}, but
  decompresses the incoming data using GZIP.