code: protected boolean hasError(HttpStatus statusCode) {
  		return (statusCode.series() == HttpStatus.Series.CLIENT_ERROR ||
  				statusCode.series() == HttpStatus.Series.SERVER_ERROR);
  	}
docs: Template method called from {@link #hasError(ClientHttpResponse)}.
  <p>The default implementation checks if the given status code is
  {@link org.springframework.http.HttpStatus.Series#CLIENT_ERROR CLIENT_ERROR}
  or {@link org.springframework.http.HttpStatus.Series#SERVER_ERROR SERVER_ERROR}.
  Can be overridden in subclasses.
  @param statusCode the HTTP status code
  @return {@code true} if the response has an error; {@code false} otherwise