code: public boolean isHttpSuccess() {
  		if (isRevisitDigest() && (getDuplicatePayload() != null)) {
  			return getDuplicatePayload().isHttpSuccess();
  		}
  		String httpCode = getHttpCode();
  		return (httpCode.startsWith("2"));
  	}
docs: {@code true} if HTTP response code is {@code 2xx}.
  @return