Make Gson special config conditional on Boot 1.5

That was the samples still work with Spring Boot 2.0.0.

Fixes gh-157 (but we should add some tests)

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

@@ -22,6 +22,7 @@ import java.util.function.Supplier;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.reactivestreams.Publisher;
 
 import org.springframework.cloud.function.context.catalog.FunctionInspector;
 import org.springframework.cloud.function.context.message.MessageUtils;
@@ -99,7 +100,7 @@ public class FunctionController {
 
 	@GetMapping(path = "/**")
 	@ResponseBody
-	public Object get(
+	public Publisher<?> get(
 			@RequestAttribute(required = false, name = "org.springframework.cloud.function.web.flux.constants.WebRequestConstants.function") Function<Flux<?>, Flux<?>> function,
 			@RequestAttribute(required = false, name = "org.springframework.cloud.function.web.flux.constants.WebRequestConstants.supplier") Supplier<Flux<?>> supplier,
 			@RequestAttribute(required = false, name = "org.springframework.cloud.function.web.flux.constants.WebRequestConstants.argument") String argument) {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2016-2017 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.
@@ -22,42 +22,57 @@ import java.io.OutputStreamWriter;
 import java.io.Reader;
 import java.lang.reflect.Type;
 import java.nio.charset.Charset;
+import java.util.ArrayList;
+import java.util.List;
 
 import com.google.gson.Gson;
 import com.google.gson.JsonIOException;
 import com.google.gson.JsonParseException;
 import com.google.gson.reflect.TypeToken;
 
+import org.springframework.boot.autoconfigure.AutoConfigureBefore;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
+import org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpInputMessage;
 import org.springframework.http.HttpOutputMessage;
 import org.springframework.http.MediaType;
 import org.springframework.http.converter.AbstractGenericHttpMessageConverter;
+import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.HttpMessageNotReadableException;
 import org.springframework.http.converter.HttpMessageNotWritableException;
+import org.springframework.http.converter.json.GsonHttpMessageConverter;
 import org.springframework.util.Assert;
 
-/**
+// TODO: remove this when https://jira.spring.io/browse/SPR-16529 is resolved
- * Implementation of {@link org.springframework.http.converter.HttpMessageConverter} that
+@Configuration
- * can read and write JSON using the
+@ConditionalOnClass(HttpMessageConverters.class)
- * <a href="https://code.google.com/p/google-gson/">Google Gson</a> library's {@link Gson}
+@AutoConfigureBefore(HttpMessageConvertersAutoConfiguration.class)
- * class.
+public class GsonHttpMessageConvertersAutoConfiguration {
- *
+
- * <p>
+	@Bean
- * This converter can be used to bind to typed beans or untyped {@code HashMap}s. By
+	public HttpMessageConverters httpMessageConverters(Gson gson) {
- * default, it supports {@code application/json} and {@code application/*+json} with
+		List<HttpMessageConverter<?>> converters = new ArrayList<>();
- * {@code UTF-8} character set.
+		for (HttpMessageConverter<?> converter : new HttpMessageConverters()
- *
+				.getConverters()) {
- * <p>
+			if (converter instanceof GsonHttpMessageConverter) {
- * Tested against Gson 2.6; compatible with Gson 2.0 and higher.
+				BetterGsonHttpMessageConverter gsonConverter = new BetterGsonHttpMessageConverter();
- *
+				gsonConverter.setGson(gson);
- * @author Roy Clarkson
+				converters.add(gsonConverter);
- * @since 4.1
+			}
- * @see #setGson
+			else {
- * @see #setSupportedMediaTypes
+				converters.add(converter);
- */
+			}
-public class BetterGsonHttpMessageConverter
+		}
-		extends AbstractGenericHttpMessageConverter<Object> {
+		return new HttpMessageConverters(false, converters);
+	}
+
+}
+
+class BetterGsonHttpMessageConverter extends AbstractGenericHttpMessageConverter<Object> {
 
 	public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
 

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

@@ -24,13 +24,11 @@ import com.google.gson.Gson;
 import org.springframework.beans.factory.SmartInitializingSingleton;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
-import org.springframework.boot.autoconfigure.AutoConfigureBefore;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
 import org.springframework.boot.autoconfigure.web.HttpMessageConverters;
-import org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration;
 import org.springframework.cloud.function.context.FunctionCatalog;
 import org.springframework.cloud.function.context.catalog.FunctionInspector;
 import org.springframework.cloud.function.web.flux.request.FluxHandlerMethodArgumentResolver;
@@ -41,8 +39,6 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.support.DefaultConversionService;
-import org.springframework.http.converter.HttpMessageConverter;
-import org.springframework.http.converter.json.GsonHttpMessageConverter;
 import org.springframework.util.ClassUtils;
 import org.springframework.web.method.support.AsyncHandlerMethodReturnValueHandler;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
@@ -58,7 +54,6 @@ import reactor.core.publisher.Flux;
 @Configuration
 @ConditionalOnWebApplication
 @ConditionalOnClass({ Flux.class, AsyncHandlerMethodReturnValueHandler.class })
-@AutoConfigureBefore(HttpMessageConvertersAutoConfiguration.class)
 @Import(FunctionController.class)
 public class ReactorAutoConfiguration {
 
@@ -78,24 +73,6 @@ public class ReactorAutoConfiguration {
 		return new BasicStringConverter(inspector, beanFactory);
 	}
 
-	// TODO: remove this when https://jira.spring.io/browse/SPR-16529 is resolved
-	@Bean
-	public HttpMessageConverters httpMessageConverters(Gson gson) {
-		List<HttpMessageConverter<?>> converters = new ArrayList<>();
-		for (HttpMessageConverter<?> converter : new HttpMessageConverters()
-				.getConverters()) {
-			if (converter instanceof GsonHttpMessageConverter) {
-				BetterGsonHttpMessageConverter gsonConverter = new BetterGsonHttpMessageConverter();
-				gsonConverter.setGson(gson);
-				converters.add(gsonConverter);
-			}
-			else {
-				converters.add(converter);
-			}
-		}
-		return new HttpMessageConverters(false, converters);
-	}
-
 	@Configuration
 	@ConditionalOnMissingClass("org.springframework.core.ReactiveAdapter")
 	protected static class FluxReturnValueConfiguration {

spring-cloud-function-web/src/main/resources/META-INF/spring.factories

@@ -1,2 +1,3 @@
 org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
-org.springframework.cloud.function.web.flux.ReactorAutoConfiguration
+org.springframework.cloud.function.web.flux.ReactorAutoConfiguration,\
+org.springframework.cloud.function.web.flux.GsonHttpMessageConvertersAutoConfiguration