PR-605 less formatting

Resolves #605

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistry.java

@@ -596,7 +596,7 @@ public class SimpleFunctionRegistry implements FunctionRegistry, FunctionInspect
 				if (result instanceof Message) {
 					Map<String, Object> headersMap = (Map<String, Object>) ReflectionUtils
 							.getField(SimpleFunctionRegistry.this.headersField, ((Message) result).getHeaders());
-					headersMap.putAll(this.sanitizeHeaders(((Message) input).getHeaders()));
+					this.sanitizeHeaders(((Message) input).getHeaders()).forEach((k, v) -> headersMap.putIfAbsent(k, v));
 				}
 				else {
 					result = MessageBuilder.withPayload(result).copyHeaders(this.sanitizeHeaders(((Message) input).getHeaders())).build();

spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/catalog/SimpleFunctionRegistryTests.java

@@ -311,6 +311,7 @@ public class SimpleFunctionRegistryTests {
 		assertThat(function).isNotNull();
 	}
 
+	@SuppressWarnings("unchecked")
 	@Test
 	public void lookupWithCompositionFunctionAndConsumer() {
 		SimpleFunctionRegistry functionRegistry = new SimpleFunctionRegistry(this.conversionService, this.messageConverter,
@@ -347,6 +348,22 @@ public class SimpleFunctionRegistryTests {
 		functionWrapper.apply("123");
 	}
 
+	@SuppressWarnings({ "rawtypes", "unchecked" })
+	@Test
+	public void testHeaderEnricherFunction() {
+		FunctionRegistration<HeaderEnricherFunction> registration =
+			new FunctionRegistration<>(new HeaderEnricherFunction(), "headerEnricher")
+				.type(FunctionType.of(HeaderEnricherFunction.class));
+		SimpleFunctionRegistry catalog = new SimpleFunctionRegistry(this.conversionService, this.messageConverter,
+			new JacksonMapper(new ObjectMapper()));
+		catalog.register(registration);
+		Function<Message<?>, Message<?>> function = catalog.lookup("headerEnricher");
+		Message<?> message =
+			function.apply(MessageBuilder.withPayload("hello").setHeader("original", "originalValue")
+				.build());
+		assertThat(message.getHeaders().get("original")).isEqualTo("newValue");
+	}
+
 
 	public Function<String, String> uppercase() {
 		return v -> v.toUpperCase();
@@ -501,4 +518,13 @@ public class SimpleFunctionRegistryTests {
 				.map(lst -> lst.stream().map(Person::getName).collect(Collectors.toList()));
 		}
 	}
+
+	private static class HeaderEnricherFunction implements Function<Message<?>, Message<?>> {
+
+		@Override
+		public Message<?> apply(Message<?> message) {
+			return MessageBuilder.withPayload(message.getPayload()).setHeader("original", "newValue")
+				.build();
+		}
+	}
 }

spring-cloud-function-context/src/test/java/org/springframework/cloud/function/userissues/UserIssuesTests.java

@@ -22,6 +22,7 @@ import java.util.function.Function;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Flux;
 
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.builder.SpringApplicationBuilder;
@@ -34,7 +35,6 @@ import org.springframework.core.ResolvableType;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.support.GenericMessage;
 
-import reactor.core.publisher.Flux;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -104,9 +104,9 @@ public class UserIssuesTests {
 		FunctionCatalog catalog = this.configureCatalog(Issue601Configuration.class);
 		FunctionInvocationWrapper function = catalog.lookup("uppercase");
 		assertThat(function.getInputType().getTypeName())
-			.isEqualTo(ResolvableType.forClassWithGenerics(Flux.class, String.class).getType().getTypeName());
+				.isEqualTo(ResolvableType.forClassWithGenerics(Flux.class, String.class).getType().getTypeName());
 		assertThat(function.getOutputType().getTypeName())
-		.isEqualTo(ResolvableType.forClassWithGenerics(Flux.class, Integer.class).getType().getTypeName());
+				.isEqualTo(ResolvableType.forClassWithGenerics(Flux.class, Integer.class).getType().getTypeName());
 		Flux<Integer> result = (Flux<Integer>) function.apply(Flux.just("julien", "ricky", "bubbles"));
 		List<Integer> results = result.collectList().block();
 		assertThat(results.get(0)).isEqualTo(6);
@@ -114,7 +114,6 @@ public class UserIssuesTests {
 		assertThat(results.get(2)).isEqualTo(7);
 	}
 
-
 	@EnableAutoConfiguration
 	@Configuration
 	public static class Issue602Configuration {
@@ -133,17 +132,17 @@ public class UserIssuesTests {
 	@Configuration
 	public static class Issue601Configuration {
 		@Bean
-	    public Uppercase uppercase() {
-	        return new Uppercase();
-	    }
+		public Uppercase uppercase() {
+			return new Uppercase();
+		}
 	}
 
 	public static class Uppercase implements Function<Flux<String>, Flux<Integer>> {
 
-	    @Override
-	    public Flux<Integer> apply(Flux<String> s) {
-	        return s.map(v -> v.length());
-	    }
+		@Override
+		public Flux<Integer> apply(Flux<String> s) {
+			return s.map(v -> v.length());
+		}
 	}
 
 	public static class Product {