code: private static <T> T nullForNotFound(IOException exception) {
      ComputeException serviceException = translate(exception);
      if (serviceException.getCode() == HTTP_NOT_FOUND) {
        return null;
      }
      throw serviceException;
    }
docs: This method returns {@code null} if the error code of {@code exception} was 404, re-throws the
  exception otherwise.
  
  @throws ComputeException if the error code of {@code exception} was not 404