Inform developers about hst component rendering waste

protected void processWindowsRender(final HstContainerConfig requestContainerConfig,
                                        final HstComponentWindow[] sortedComponentWindows, final Map<HstComponentWindow, HstRequest> requestMap,
                                        final Map<HstComponentWindow, HstResponse> responseMap) throws ContainerException {

        for (int i = sortedComponentWindows.length - 1; i >= 0; i--) {
            HstComponentWindow window = sortedComponentWindows[i];
            if (!window.isVisible()) {
                continue;
            }

            HstRequest request = requestMap.get(window);
            if (isAsync(window, request)) {
                continue;
            }
            HstResponse response = responseMap.get(window);
            getComponentInvoker().invokeRender(requestContainerConfig, request, response);

            if (log.isWarnEnabled()) {
                if (window.getChildWindowMap() != null) {
                    for (HstComponentWindow childWindow : window.getChildWindowMap().values()) {
                        final HstResponse childResponse = responseMap.get(childWindow);
                        if (!(childResponse instanceof HstResponseImpl)) {
                            continue;
                        }
                        final HstResponseImpl childResponseImpl = (HstResponseImpl)childResponse;
                        if (!childWindow.getResponseState().isFlushed() && StringUtils.isNotBlank(getRenderer(childWindow, childResponseImpl))) {
                            if (childResponse.getHeadElements() == null || childResponse.getHeadElements().isEmpty()) {
                                // there is a window with a renderer but the content is never included in its ancestor component : That
                                // is a waste. Hence this warning
                                log.warn("Component '{}' gets rendered but never adds anything to the response. Component id is '{}' " +
                                        " and renderer '{}' is never flushed to a parent component. This is waste.",
                                        new String[]{childWindow.getName(), childWindow.getComponentInfo().getId(), getRenderer(childWindow, childResponseImpl)});
                            } else {
                                // there is a window with a renderer but the content is never included in its ancestor component apart from some
                                // head elements : this is potential waste and unintended behavior has this info
                                log.info("Component '{}' gets rendered but except for some head element(s) adds nothing to the response. Component id is '{}' " +
                                        " and renderer '{}' is never flushed to a parent component. This component might be waste.",
                                        new String[]{childWindow.getName(), childWindow.getComponentInfo().getId(), getRenderer(childWindow, childResponseImpl)});
                            }
                        }
                    }
                }
            }

        }
    }

 private String getRenderer(final HstComponentWindow window, final HstResponseImpl hstResponse) {
        String dispatchUrl = hstResponse.getRenderPath();
        if (StringUtils.isNotBlank(dispatchUrl)) {
            return dispatchUrl;
        }
        dispatchUrl = window.getRenderPath();
        if (StringUtils.isNotBlank(dispatchUrl)) {
            return dispatchUrl;
        }
        return window.getNamedRenderer();
    }