Add support for feign OptionalDecoder

spring-cloud-netflix-core/pom.xml

@@ -115,6 +115,11 @@
 			<optional>true</optional>
 		</dependency>
 		<dependency>
+			<groupId>io.github.openfeign</groupId>
+			<artifactId>feign-java8</artifactId>
+			<optional>true</optional>
+		</dependency>
+		<dependency>
 			<groupId>com.netflix.hystrix</groupId>
 			<artifactId>hystrix-core</artifactId>
 			<optional>true</optional>

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/FeignClientsConfiguration.java

@@ -46,6 +46,7 @@ import feign.Retryer;
 import feign.codec.Decoder;
 import feign.codec.Encoder;
 import feign.hystrix.HystrixFeign;
+import feign.optionals.OptionalDecoder;
 
 /**
  * @author Dave Syer
@@ -69,7 +70,7 @@ public class FeignClientsConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	public Decoder feignDecoder() {
-		return new ResponseEntityDecoder(new SpringDecoder(this.messageConverters));
+		return new OptionalDecoder(new ResponseEntityDecoder(new SpringDecoder(this.messageConverters)));
 	}
 
 	@Bean

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/EnableFeignClientsTests.java

@@ -23,7 +23,6 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.cloud.netflix.archaius.ArchaiusAutoConfiguration;
-import org.springframework.cloud.netflix.feign.support.ResponseEntityDecoder;
 import org.springframework.cloud.netflix.feign.support.SpringEncoder;
 import org.springframework.cloud.netflix.feign.support.SpringMvcContract;
 import org.springframework.context.annotation.Configuration;
@@ -36,6 +35,7 @@ import feign.Feign;
 import feign.Logger;
 import feign.codec.Decoder;
 import feign.codec.Encoder;
+import feign.optionals.OptionalDecoder;
 import feign.slf4j.Slf4jLogger;
 
 /**
@@ -51,7 +51,7 @@ public class EnableFeignClientsTests {
 
 	@Test
 	public void decoderDefaultCorrect() {
-		ResponseEntityDecoder.class
+		OptionalDecoder.class
 				.cast(this.feignContext.getInstance("foo", Decoder.class));
 	}
 

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/FeignClientOverrideDefaultsTests.java

@@ -17,17 +17,12 @@
 
 package org.springframework.cloud.netflix.feign;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.cloud.netflix.archaius.ArchaiusAutoConfiguration;
-import org.springframework.cloud.netflix.feign.support.ResponseEntityDecoder;
 import org.springframework.cloud.netflix.feign.support.SpringEncoder;
 import org.springframework.cloud.netflix.feign.support.SpringMvcContract;
 import org.springframework.context.annotation.Bean;
@@ -38,6 +33,10 @@ import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
 import feign.Contract;
 import feign.Feign;
 import feign.Logger;
@@ -51,6 +50,7 @@ import feign.codec.Decoder;
 import feign.codec.Encoder;
 import feign.codec.ErrorDecoder;
 import feign.hystrix.HystrixFeign;
+import feign.optionals.OptionalDecoder;
 import feign.slf4j.Slf4jLogger;
 
 /**
@@ -79,7 +79,7 @@ public class FeignClientOverrideDefaultsTests {
 	@Test
 	public void overrideDecoder() {
 		Decoder.Default.class.cast(this.context.getInstance("foo", Decoder.class));
-		ResponseEntityDecoder.class.cast(this.context.getInstance("bar", Decoder.class));
+		OptionalDecoder.class.cast(this.context.getInstance("bar", Decoder.class));
 	}
 
 	@Test

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/valid/FeignClientTests.java

@@ -16,14 +16,6 @@
 
 package org.springframework.cloud.netflix.feign.valid;
 
-import static org.hamcrest.Matchers.instanceOf;
-import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertThat;
-import static org.junit.Assert.assertTrue;
-
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
@@ -34,6 +26,7 @@ import java.util.Collection;
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 
@@ -76,6 +69,15 @@ import com.netflix.hystrix.HystrixCommandKey;
 import com.netflix.loadbalancer.Server;
 import com.netflix.loadbalancer.ServerList;
 
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.hamcrest.Matchers.instanceOf;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
 import feign.Client;
 import feign.Feign;
 import feign.Logger;
@@ -161,6 +163,9 @@ public class FeignClientTests {
 		@RequestMapping(method = RequestMethod.GET, path = "/hello")
 		Hello getHello();
 
+		@RequestMapping(method = RequestMethod.GET, path = "/hello")
+		Optional<Hello> getOptionalHello();
+
 		@RequestMapping(method = RequestMethod.GET, path = "${feignClient.methodLevelRequestMappingPath}")
 		Hello getHelloUsingPropertyPlaceHolder();
 
@@ -240,6 +245,9 @@ public class FeignClientTests {
 	protected interface DecodingTestClient {
 		@RequestMapping(method = RequestMethod.GET, path = "/notFound")
 		ResponseEntity<String> notFound();
+
+		@RequestMapping(method = RequestMethod.GET, path = "/notFound")
+		Optional<String> optional();
 	}
 
 	@FeignClient(name = "localapp3", fallback = HystrixClientFallback.class)
@@ -519,6 +527,15 @@ public class FeignClientTests {
 	}
 
 	@Test
+	public void testOptional() {
+		Optional<Hello> hello = this.testClient.getOptionalHello();
+		assertThat(hello)
+				.isNotNull()
+				.isPresent()
+				.contains(new Hello(HELLO_WORLD_1));
+	}
+
+	@Test
 	public void testGenericType() {
 		List<Hello> hellos = this.testClient.getHellos();
 		assertNotNull("hellos was null", hellos);
@@ -633,6 +650,12 @@ public class FeignClientTests {
 	}
 
 	@Test
+	public void testOptionalNotFound() {
+		Optional<String> s = decodingTestClient.optional();
+		assertThat(s).isNotPresent();
+	}
+
+	@Test
 	public void testConvertingExpander() {
 		assertEquals(Arg.A.toString(), testClient.getToString(Arg.A));
 		assertEquals(Arg.B.toString(), testClient.getToString(Arg.B));

spring-cloud-netflix-dependencies/pom.xml

@@ -16,7 +16,7 @@
 	<properties>
 		<archaius.version>0.7.5</archaius.version>
 		<eureka.version>1.8.2</eureka.version>
-		<feign.version>9.5.0</feign.version>
+		<feign.version>9.5.1</feign.version>
 		<hystrix.version>1.5.12</hystrix.version>
 		<ribbon.version>2.2.2</ribbon.version>
 		<servo.version>0.10.1</servo.version>
@@ -283,6 +283,11 @@
 			</dependency>
 			<dependency>
 				<groupId>io.github.openfeign</groupId>
+				<artifactId>feign-java8</artifactId>
+				<version>${feign.version}</version>
+			</dependency>
+			<dependency>
+				<groupId>io.github.openfeign</groupId>
 				<artifactId>feign-okhttp</artifactId>
 				<version>${feign.version}</version>
 			</dependency>

spring-cloud-starter-netflix/spring-cloud-starter-openfeign/pom.xml

@@ -47,6 +47,10 @@
 			<artifactId>feign-hystrix</artifactId>
 		</dependency>
 		<dependency>
+			<groupId>io.github.openfeign</groupId>
+			<artifactId>feign-java8</artifactId>
+		</dependency>
+		<dependency>
 			<groupId>org.springframework.cloud</groupId>
 			<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
 		</dependency>