Return HandlerResult in HandlerAdapter#handle()

This commit updates HandlerAdapter#handle() to return HandlerResult
instead of Publisher<HandlerResult>. A new SimpleHandlerResultHandler
class has been introduced for handlers returning Publisher<Void>.

spring-web-reactive/src/test/java/org/springframework/reactive/web/dispatch/handler/SimpleUrlHandlerMappingIntegrationTests.java

@@ -28,6 +28,7 @@ import reactor.rx.Streams;
 import org.springframework.http.RequestEntity;
 import org.springframework.http.ResponseEntity;
 import org.springframework.reactive.web.dispatch.DispatcherHandler;
+import org.springframework.reactive.web.dispatch.SimpleHandlerResultHandler;
 import org.springframework.reactive.web.http.AbstractHttpHandlerIntegrationTests;
 import org.springframework.reactive.web.http.HttpHandler;
 import org.springframework.reactive.web.http.ServerHttpRequest;
@@ -52,6 +53,7 @@ public class SimpleUrlHandlerMappingIntegrationTests extends AbstractHttpHandler
 		StaticWebApplicationContext wac = new StaticWebApplicationContext();
 		wac.registerSingleton("hm", TestHandlerMapping.class);
 		wac.registerSingleton("ha", HttpHandlerAdapter.class);
+		wac.registerSingleton("hhrh", SimpleHandlerResultHandler.class);
 		wac.refresh();
 
 		DispatcherHandler dispatcherHandler = new DispatcherHandler();

spring-web-reactive/src/test/java/org/springframework/reactive/web/dispatch/method/annotation/ResponseBodyResultHandlerTests.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2002-2015 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.reactive.web.dispatch.method.annotation;
+
+import java.util.Collections;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import org.junit.Test;
+import org.reactivestreams.Publisher;
+
+import org.springframework.reactive.web.dispatch.HandlerResult;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.method.HandlerMethod;
+
+/**
+ * @author Sebastien Deleuze
+ */
+public class ResponseBodyResultHandlerTests {
+
+	@Test
+	public void supports() throws NoSuchMethodException {
+		ResponseBodyResultHandler resultHandler = new ResponseBodyResultHandler(Collections.emptyList());
+		TestController controller = new TestController();
+
+		HandlerMethod notAnnotatedMethod = new HandlerMethod(controller, TestController.class.getMethod("notAnnotated"));
+		assertFalse(resultHandler.supports(new HandlerResult(notAnnotatedMethod, null)));
+
+		HandlerMethod publisherStringMethod = new HandlerMethod(controller, TestController.class.getMethod("publisherString"));
+		assertTrue(resultHandler.supports(new HandlerResult(publisherStringMethod, null)));
+
+		HandlerMethod publisherVoidMethod = new HandlerMethod(controller, TestController.class.getMethod("publisherVoid"));
+		assertFalse(resultHandler.supports(new HandlerResult(publisherVoidMethod, null)));
+	}
+
+
+	private static class TestController {
+
+		public Publisher<String> notAnnotated() {
+			return null;
+		}
+
+		@ResponseBody
+		public Publisher<String> publisherString() {
+			return null;
+		}
+
+		@ResponseBody
+		public Publisher<Void> publisherVoid() {
+			return null;
+		}
+	}
+
+}