@SuppressWarnings("unchecked")
 public <T extends RpcService> RpcRouter<T> getRpcRouter(Class<T> type) {
   RpcRouter<?> potentialRouter = rpcRouters.get(type);
   if (potentialRouter != null) {
     return (RpcRouter<T>) potentialRouter;
   }
   synchronized (this) {
     /**
      * Potential Router could be instantiated by other thread while we were waiting for the lock.
      */
     potentialRouter = rpcRouters.get(type);
     if (potentialRouter != null) {
       return (RpcRouter<T>) potentialRouter;
     }
     RpcRouter<T> router = rpcFactory.getRouterFor(type, name);
     router.registerRouteChangeListener(new RouteChangeForwarder(type));
     LOG.debug(
         "Registering router {} as global implementation of {} in {}",
         router,
         type.getSimpleName(),
         this);
     RuntimeCodeHelper.setDelegate(getRpcService(type), router.getInvocationProxy());
     rpcRouters.put(type, router);
     notifyListenersRoutedCreated(router);
     return router;
   }
 }
 @Override
 public final <T extends RpcService> RpcRegistration<T> addRpcImplementation(
     Class<T> type, T implementation) throws IllegalStateException {
   @SuppressWarnings("unchecked")
   RpcRouter<T> potentialRouter = (RpcRouter<T>) rpcRouters.get(type);
   if (potentialRouter != null) {
     checkState(
         potentialRouter.getDefaultService() == null,
         "Default service for routed RPC already registered.");
     return potentialRouter.registerDefaultService(implementation);
   }
   T publicProxy = getRpcService(type);
   RpcService currentDelegate = RuntimeCodeHelper.getDelegate(publicProxy);
   checkState(currentDelegate == null, "Rpc service is already registered");
   LOG.debug(
       "Registering {} as global implementation of {} in {}",
       implementation,
       type.getSimpleName(),
       this);
   RuntimeCodeHelper.setDelegate(publicProxy, implementation);
   notifyGlobalRpcAdded(type);
   return new RpcProxyRegistration<T>(type, implementation, this);
 }