protected com.yahoo.jdisc.http.HttpRequest asHttpRequest(Request request) {
        if (!(request instanceof com.yahoo.jdisc.http.HttpRequest)) {
            throw new IllegalArgumentException("Expected " + com.yahoo.jdisc.http.HttpRequest.class.getName() +
                                               ", got " + request.getClass().getName());
        }
        return (com.yahoo.jdisc.http.HttpRequest) request;
    }
Override this to implement custom access logging.

@param startTime execution start
@param renderStartTime start of output rendering
@param response the response which the log entry regards
@param httpRequest the incoming HTTP request
@param rendererWiring the stream the rendered response is written to, used for
                      fetching length of rendered response
container-core/src/main/java/com/yahoo/container/jdisc/ThreadedHttpRequestHandler.java