Deprecated as of 5.0 a TaskScheduler is not provided upfront, not until it is obvious that it is needed, see ServletWebSocketHandlerRegistry.requiresTaskScheduler() and ServletWebSocketHandlerRegistry.setTaskScheduler(org.springframework.scheduling.TaskScheduler).
public AbstractHandlerMapping getHandlerMapping() { Map<String, Object> urlMap = new LinkedHashMap<>(); for (ServletWebSocketHandlerRegistration registration : this.registrations) { updateTaskScheduler(registration); MultiValueMap<HttpRequestHandler, String> mappings = registration.getMappings(); mappings.forEach((httpHandler, patterns) -> { for (String pattern : patterns) { urlMap.put(pattern, httpHandler); } }); } WebSocketHandlerMapping hm = new WebSocketHandlerMapping(); hm.setUrlMap(urlMap); hm.setOrder(this.order); if (this.urlPathHelper != null) { hm.setUrlPathHelper(this.urlPathHelper); } return hm; }