From a2dc34a160a07181dc4953f504010622c5700ce9 Mon Sep 17 00:00:00 2001
From: Oleg Zhurakousky <ozhurakousky@pivotal.io>
Date: Mon, 2 Dec 2019 12:03:37 +0100
Subject: [PATCH] GH-1852 Fix issue with 'output' channel

- This fix addresses the issue where framework assumed the existance of 'output' channel where it is not always the case
 - It also addresses the binary relationship of annotation-based and functional model where you can use one or the other, meaning
 functions will not work with annotation-based bindings with the exception of composing to the existing output (e.g., existing legacy app)
 - It alos upgrades reactor to Dysprosium-SR1

 Resolves #1852
---
 pom.xml                                              |  2 +-
 .../cloud/stream/function/FunctionConfiguration.java | 12 ++++++++----
 .../GreenfieldFunctionEnableBindingTests.java        |  4 ----
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/pom.xml b/pom.xml
index d5c515a42..91007a925 100644
--- a/pom.xml
+++ b/pom.xml
@@ -23,7 +23,7 @@
 	</scm>
 	<properties>
 		<java.version>1.8</java.version>
-		<reactor.version>Californium-SR11</reactor.version>
+		<reactor.version>Dysprosium-SR1</reactor.version>
 		<objenesis.version>2.1</objenesis.version>
 		<spring-cloud-function.version>3.0.0.RELEASE</spring-cloud-function.version>
 		<maven-checkstyle-plugin.failsOnError>true</maven-checkstyle-plugin.failsOnError>
diff --git a/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/function/FunctionConfiguration.java b/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/function/FunctionConfiguration.java
index 329d71d13..0afe6fbb6 100644
--- a/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/function/FunctionConfiguration.java
+++ b/spring-cloud-stream/src/main/java/org/springframework/cloud/stream/function/FunctionConfiguration.java
@@ -339,10 +339,14 @@ public class FunctionConfiguration {
 				messageChannel = this.context.getBean(channelName, SubscribableChannel.class);
 			}
 			else {
-				// could be "input" or "output" if subscribing to existing Source
-				messageChannel = this.context.containsBean("input")
-						? this.context.getBean("input", SubscribableChannel.class)
-								: this.context.getBean("output", SubscribableChannel.class);
+				if (this.context.containsBean("input")) {
+					logger.info("@EnableBinding way of defining channels is not supported by functions, so 'input' "
+							+ "channel will not be bound to any existing function beans. You may safely ignore this "
+							+ "message if that was not your intention otherwise, please remove @EnableBinding annotation.");
+				}
+				if (this.context.containsBean("output")) { // need this to compose to existing sources
+					messageChannel = this.context.getBean("output", SubscribableChannel.class);
+				}
 			}
 			return messageChannel;
 		}
diff --git a/spring-cloud-stream/src/test/java/org/springframework/cloud/stream/function/GreenfieldFunctionEnableBindingTests.java b/spring-cloud-stream/src/test/java/org/springframework/cloud/stream/function/GreenfieldFunctionEnableBindingTests.java
index 65fef8b90..640a50641 100644
--- a/spring-cloud-stream/src/test/java/org/springframework/cloud/stream/function/GreenfieldFunctionEnableBindingTests.java
+++ b/spring-cloud-stream/src/test/java/org/springframework/cloud/stream/function/GreenfieldFunctionEnableBindingTests.java
@@ -36,8 +36,6 @@ import org.springframework.cloud.stream.binder.test.InputDestination;
 import org.springframework.cloud.stream.binder.test.OutputDestination;
 import org.springframework.cloud.stream.binder.test.TestChannelBinderConfiguration;
 import org.springframework.cloud.stream.converter.CompositeMessageConverterFactory;
-import org.springframework.cloud.stream.messaging.Processor;
-import org.springframework.cloud.stream.messaging.Sink;
 import org.springframework.cloud.stream.messaging.Source;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -176,7 +174,6 @@ public class GreenfieldFunctionEnableBindingTests {
 	}
 
 	@EnableAutoConfiguration
-	@EnableBinding(Processor.class)
 	public static class ProcessorFromFunction {
 
 		@Bean
@@ -187,7 +184,6 @@ public class GreenfieldFunctionEnableBindingTests {
 	}
 
 	@EnableAutoConfiguration
-	@EnableBinding(Sink.class)
 	public static class SinkFromConsumer {
 
 		@Bean