/**
* Lookup parameter.
*/
protected Object get(HttpServletRequest request, Object key) {
PanelsContext context = support.getContext(request);
ParamConfig param = context.lookupParamConfig(key.toString());
if (param == null) {
throw new AccessException("Unknown panel parameter '" + key + "'");
}
if (!param.isDefined()) {
throw new AccessException("Undefined value for panel parameter '" + key + "'");