GH-499,498 Add support for SupplierExporter to control output content-type

- Add 'contentType' property to ExporterProperties to assist SupplierExporter with delegating it to function catalog
- Add additional logging and testing
- Change JsonMapper to abstract class providing special handling of conversion of Json Sting to byte[]

spring-cloud-function-web/src/main/java/org/springframework/cloud/function/web/RequestProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -127,8 +127,10 @@ public class RequestProcessor {
 
 	public Mono<ResponseEntity<?>> post(FunctionWrapper wrapper,
 			ServerWebExchange exchange) {
-		return Mono.from(body(wrapper.handler(), exchange))
+		Mono<ResponseEntity<?>> responseEntity = Mono.from(body(wrapper.handler(), exchange))
 				.flatMap(body -> response(wrapper, body, false));
+
+		return responseEntity;
 	}
 
 	public Mono<ResponseEntity<?>> post(FunctionWrapper wrapper, String body,
@@ -149,7 +151,7 @@ public class RequestProcessor {
 					jsonType = ResolvableType.forClassWithGenerics((Class<?>) jsonType,
 							(Class<?>) itemType).getType();
 				}
-				input = this.mapper.toObject((String) input, jsonType);
+				input = this.mapper.fromJson((String) input, jsonType);
 			}
 			else {
 				input = this.converter.convert(function, (String) input);
@@ -178,7 +180,6 @@ public class RequestProcessor {
 
 	private Mono<ResponseEntity<?>> response(FunctionWrapper request, Object handler,
 			Publisher<?> result, Boolean single, boolean getter) {
-
 		BodyBuilder builder = ResponseEntity.ok();
 		if (this.inspector.isMessage(handler)) {
 			result = Flux.from(result)
@@ -389,7 +390,11 @@ public class RequestProcessor {
 								exchange.getLogPrefix() + "0..1 [" + elementType + "]");
 					}
 					Mono<?> mono = reader.readMono(actualType, elementType, request,
-							response, readHints);
+							response, readHints).doOnNext(v -> {
+								if (logger.isDebugEnabled()) {
+									logger.debug("received: " + v);
+								}
+							});
 					mono = mono.onErrorResume(
 							ex -> Mono.error(handleReadError(bodyParam, ex)));
 					if (isBodyRequired) {

spring-cloud-function-web/src/main/java/org/springframework/cloud/function/web/flux/FunctionController.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.

spring-cloud-function-web/src/main/java/org/springframework/cloud/function/web/source/ExporterProperties.java

@@ -24,6 +24,7 @@ import org.springframework.cloud.function.context.FunctionProperties;
 
 /**
  * @author Dave Syer
+ * @author Oleg Zhurakousky
  *
  */
 @ConfigurationProperties(prefix = FunctionProperties.PREFIX + ".web.export")
@@ -149,6 +150,11 @@ public class ExporterProperties {
 		 */
 		private String name;
 
+		/**
+		 * Content type to use when serializing source's output for transport (default 'application/json`).
+		 */
+		private String contentType = "application/json";
+
 		public String getName() {
 			return this.name;
 		}
@@ -169,6 +175,13 @@ public class ExporterProperties {
 			return this.headers;
 		}
 
+		public String getContentType() {
+			return contentType;
+		}
+
+		public void setContentType(String contentType) {
+			this.contentType = contentType;
+		}
 	}
 
 }

spring-cloud-function-web/src/main/java/org/springframework/cloud/function/web/source/SupplierExporter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -58,6 +58,8 @@ public class SupplierExporter implements SmartLifecycle {
 
 	private final String supplier;
 
+	private final String contentType;
+
 	private volatile boolean running;
 
 	private volatile boolean ok = true;
@@ -70,14 +72,15 @@ public class SupplierExporter implements SmartLifecycle {
 
 	SupplierExporter(RequestBuilder requestBuilder,
 			DestinationResolver destinationResolver, FunctionCatalog catalog,
-			WebClient client, ExporterProperties props) {
+			WebClient client, ExporterProperties exporterProperties) {
 		this.requestBuilder = requestBuilder;
 		this.destinationResolver = destinationResolver;
 		this.catalog = catalog;
 		this.client = client;
-		this.debug = props.isDebug();
-		this.autoStartup = props.isAutoStartup();
-		this.supplier = props.getSink().getName();
+		this.debug = exporterProperties.isDebug();
+		this.autoStartup = exporterProperties.isAutoStartup();
+		this.supplier = exporterProperties.getSink().getName();
+		this.contentType = exporterProperties.getSink().getContentType();
 	}
 
 	@Override
@@ -93,7 +96,7 @@ public class SupplierExporter implements SmartLifecycle {
 
 		boolean suppliersPresent = false;
 		for (String name : names) {
-			Supplier<Publisher<Object>> supplier = this.catalog.lookup(Supplier.class, name);
+			Supplier<Publisher<Object>> supplier = this.catalog.lookup(name, this.contentType);
 			if (supplier == null) {
 				logger.warn("No such Supplier: " + name);
 				continue;
@@ -163,8 +166,7 @@ public class SupplierExporter implements SmartLifecycle {
 
 	private Flux<ClientResponse> forward(Supplier<Publisher<Object>> supplier, String name) {
 		return Flux.from(supplier.get()).flatMap(value -> {
-			String destination = this.destinationResolver.destination(supplier, name,
-					value);
+			String destination = this.destinationResolver.destination(supplier, name, value);
 			if (this.debug) {
 				logger.info("Posting to: " + destination);
 			}
@@ -178,9 +180,17 @@ public class SupplierExporter implements SmartLifecycle {
 			Message<?> message = (Message<?>) value;
 			body = message.getPayload();
 		}
+		if (this.debug) {
+			logger.debug("Sending BODY as type: " + body.getClass().getName());
+		}
 		Mono<ClientResponse> result = this.client.post().uri(uri)
 				.headers(headers -> headers(headers, destination, value)).bodyValue(body)
-				.exchange();
+				.exchange()
+				.doOnNext(response -> {
+					if (this.debug) {
+						logger.debug("Response STATUS: " + response.statusCode());
+					}
+				});
 		if (this.debug) {
 			result = result.log();
 		}

spring-cloud-function-web/src/test/java/org/springframework/cloud/function/test/FunctionalExporterTests.java

@@ -52,6 +52,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 		"spring.cloud.function.web.export.sink.url=http://localhost:${my.port}",
 		"spring.cloud.function.web.export.source.url=http://localhost:${my.port}",
 		"spring.cloud.function.web.export.sink.name=origin|uppercase",
+		"spring.cloud.function.web.export.sink.contentType=text/plain",
 		"spring.cloud.function.web.export.debug=true" })
 public class FunctionalExporterTests {
 

spring-cloud-function-web/src/test/java/org/springframework/cloud/function/web/source/FunctionAutoConfigurationIntegrationTests.java

@@ -85,8 +85,8 @@ public class FunctionAutoConfigurationIntegrationTests {
 		}
 		// It completed
 		assertThat(this.forwarder.isOk()).isTrue();
-		assertThat(this.app.inputs).contains("HELLO");
-		assertThat(this.app.inputs).contains("WORLD");
+		assertThat(this.app.inputs).contains("\"HELLO\"");
+		assertThat(this.app.inputs).contains("\"WORLD\"");
 	}
 
 	@EnableAutoConfiguration