question: public CompletableFuture < Void > destroy ( ) { CompletableFuture < Void > ret ; if ( controllerProxy != null ) { ret = controllerProxy . destroy ( ) ; controllerProxy = null ; } else { ret = new CompletableFuture < > ( ) ; ret . complete ( null ) ; } return ret ; }
target:  By calling this method the MVC group will be destroyed. This means that the controller instance on the server will be removed and the model that is managed and synchronized between client and server will be detached. After this method is called the view should not be used anymore. It's important to call this method to remove all the unneeded references on the server.