code: public void addStatusMapping(String statusCode, Integer httpStatus) {
  		Assert.notNull(statusCode, "StatusCode must not be null");
  		Assert.notNull(httpStatus, "HttpStatus must not be null");
  		this.statusMapping.put(statusCode, httpStatus);
  	}
docs: Add a status mapping to the existing set.
  @param statusCode the status code to map
  @param httpStatus the http status