/**
  * @return prefix for cache key that contains current controller's context (currently plugin and
  *     namespace)
  */
 protected String resolveCurrentControllerKeyPrefixes() {
   String pluginContextPath = null;
   String namespace = null;
   GrailsWebRequest webRequest = GrailsWebRequest.lookup();
   if (webRequest != null) {
     namespace = webRequest.getControllerNamespace();
     pluginContextPath =
         (webRequest.getAttributes() != null && webRequest.getCurrentRequest() != null)
             ? webRequest.getAttributes().getPluginContextPath(webRequest.getCurrentRequest())
             : null;
     return (pluginContextPath != null ? pluginContextPath : "-")
         + ","
         + (namespace != null ? namespace : "-");
   } else {
     return null;
   }
 }