SockJS TaskScheduler container bean is package private

See gh-27903

spring-websocket/src/main/java/org/springframework/web/socket/config/annotation/WebSocketConfigurationSupport.java

@@ -80,7 +80,7 @@ protected void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
 	 * </pre>
 	 */
 	@Bean
-	public DefaultSockJsSchedulerContainer defaultSockJsSchedulerContainer() {
+	DefaultSockJsSchedulerContainer defaultSockJsSchedulerContainer() {
 		return (initHandlerRegistry().requiresTaskScheduler() ?
 				new DefaultSockJsSchedulerContainer(initDefaultSockJsScheduler()) :
 				new DefaultSockJsSchedulerContainer(null));