if (headElements == null) {
headElements = super.getHeadElements();
String versionIndicator = ClickUtils.getResourceVersionIndicator(getContext());
headElements.add(new CssImport("/click/calendar/" + getStyle()
+ ".css", versionIndicator));
headElements.add(new JsImport("/click/control.js",
versionIndicator));
headElements.add(new JsImport("/click/prototype/prototype.js",
versionIndicator));