Reactive changes for samples

- Relates #750

spring-statemachine-samples/web/src/main/java/demo/web/StateMachineController.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2016 the original author or authors.
+ * Copyright 2015-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,6 +49,7 @@ import org.springframework.web.bind.annotation.ResponseStatus;
 
 import demo.web.StateMachineConfig.Events;
 import demo.web.StateMachineConfig.States;
+import reactor.core.publisher.Mono;
 
 @Controller
 public class StateMachineController {
@@ -154,7 +155,7 @@ public class StateMachineController {
 				.withPayload(id)
 				.setHeader("testVariable", testVariable)
 				.build();
-		stateMachine.sendEvent(message);
+		stateMachine.sendEvent(Mono.just(message)).subscribe();
 	}
 
 	@RequestMapping("/join")