GH-1014 Fix CustomRuntimeEventLoop to default to RoutingFunction

Resolves #1014

spring-cloud-function-samples/function-sample-aws-native/src/main/java/com/example/demo/NativeUppercaseApplication.java

@@ -2,17 +2,35 @@ package com.example.demo;
 
 import java.util.function.Function;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.cloud.function.context.DefaultMessageRoutingHandler;
+import org.springframework.cloud.function.context.MessageRoutingCallback;
 import org.springframework.context.annotation.Bean;
+import org.springframework.messaging.Message;
 
 @SpringBootApplication
 public class NativeUppercaseApplication {
 
+	Log logger = LogFactory.getLog(NativeUppercaseApplication.class);
+
 	public static void main(String[] args) {
 		SpringApplication.run(NativeUppercaseApplication.class, args);
 	}
-	
+
+	@Bean
+	public MessageRoutingCallback customRouter() {
+		return new MessageRoutingCallback() {
+			@Override
+			public String routingResult(Message<?> message) {
+				logger.info("Received message: " + message);
+				return (String) message.getHeaders().get("spring.cloud.function.definition");
+			}
+		};
+	}
+
 	@Bean
 	public Function<String, String> uppercase() {
 		return v -> {
@@ -21,4 +39,12 @@ public class NativeUppercaseApplication {
 		};
 	}
 
+	@Bean
+	public Function<String, String> lowercase() {
+		return v -> {
+			System.out.println("Lowercasing " + v);
+			return v.toUpperCase();
+		};
+	}
+
 }