Fix Feign Ribbon with Apache HTTP client

The Apcahe client does not allow empty body for PATCH, nor does it
allow a request to be pre-populated with a Content-Length. Spring
Cloud tests were trying to do the former, and Feign allows the latter.

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

@@ -59,19 +59,19 @@ public class FeignClientsConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	public Decoder feignDecoder() {
-		return new ResponseEntityDecoder(new SpringDecoder(messageConverters));
+		return new ResponseEntityDecoder(new SpringDecoder(this.messageConverters));
 	}
 
 	@Bean
 	@ConditionalOnMissingBean
 	public Encoder feignEncoder() {
-		return new SpringEncoder(messageConverters);
+		return new SpringEncoder(this.messageConverters);
 	}
 
 	@Bean
 	@ConditionalOnMissingBean
 	public Contract feignContract() {
-		return new SpringMvcContract(parameterProcessors);
+		return new SpringMvcContract(this.parameterProcessors);
 	}
 
 	@Configuration
@@ -101,9 +101,10 @@ public class FeignClientsConfiguration {
 		private HttpClient httpClient;
 
 		@ConditionalOnMissingBean
+		@Bean
 		public Client feignClient() {
-			if (httpClient != null) {
-				return new ApacheHttpClient(httpClient);
+			if (this.httpClient != null) {
+				return new ApacheHttpClient(this.httpClient);
 			}
 			return new ApacheHttpClient();
 		}

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

@@ -19,6 +19,7 @@ package org.springframework.cloud.netflix.feign.ribbon;
 import java.io.IOException;
 import java.net.URI;
 import java.util.Collection;
+import java.util.LinkedHashMap;
 import java.util.Map;
 
 import org.springframework.cloud.netflix.ribbon.ServerIntrospector;
@@ -39,6 +40,7 @@ import feign.Client;
 import feign.Request;
 import feign.RequestTemplate;
 import feign.Response;
+import feign.Util;
 
 public class FeignLoadBalancer extends
 		AbstractLoadBalancerAwareClient<FeignLoadBalancer.RibbonRequest, FeignLoadBalancer.RibbonResponse> {
@@ -112,14 +114,22 @@ public class FeignLoadBalancer extends
 
 		RibbonRequest(Client client, Request request, URI uri) {
 			this.client = client;
-			this.request = request;
 			setUri(uri);
+			this.request = toRequest(request);
+		}
+
+		private Request toRequest(Request request) {
+			Map<String, Collection<String>> headers = new LinkedHashMap<>(
+					request.headers());
+			// Apache client barfs if you set the content length
+			headers.remove(Util.CONTENT_LENGTH);
+			return new RequestTemplate().method(request.method())
+					.append(getUri().toASCIIString())
+					.body(request.body(), request.charset()).headers(headers).request();
 		}
 
 		Request toRequest() {
-			return new RequestTemplate().method(this.request.method())
-					.append(getUri().toASCIIString()).headers(this.request.headers())
-					.body(this.request.body(), this.request.charset()).request();
+			return toRequest(this.request);
 		}
 
 		Client client() {

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

@@ -63,7 +63,6 @@ public class FeignRibbonClientAutoConfiguration {
 	@Configuration
 	@ConditionalOnClass(ApacheHttpClient.class)
 	@ConditionalOnProperty(value = "feign.httpclient.enabled", matchIfMissing = true)
-	@ConditionalOnMissingBean(Client.class)
 	protected static class HttpClientConfiguration {
 
 		@Autowired(required = false)
@@ -73,6 +72,7 @@ public class FeignRibbonClientAutoConfiguration {
 		CachingSpringLoadBalancerFactory cachingFactory;
 
 		@Bean
+		@ConditionalOnMissingBean(Client.class)
 		public Client feignClient() {
 			ApacheHttpClient delegate;
 			if (this.httpClient != null) {
@@ -88,7 +88,6 @@ public class FeignRibbonClientAutoConfiguration {
 	@Configuration
 	@ConditionalOnClass(OkHttpClient.class)
 	@ConditionalOnProperty(value = "feign.okhttp.enabled", matchIfMissing = true)
-	@ConditionalOnMissingBean(Client.class)
 	protected static class OkHttpConfiguration {
 
 		@Autowired(required = false)
@@ -98,6 +97,7 @@ public class FeignRibbonClientAutoConfiguration {
 		CachingSpringLoadBalancerFactory cachingFactory;
 
 		@Bean
+		@ConditionalOnMissingBean(Client.class)
 		public Client feignClient() {
 			OkHttpClient delegate;
 			if (this.okHttpClient != null) {

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

@@ -36,7 +36,8 @@ public class LoadBalancerFeignClient implements Client {
 	private final Client delegate;
 	private CachingSpringLoadBalancerFactory lbClientFactory;
 
-	public LoadBalancerFeignClient(Client delegate, CachingSpringLoadBalancerFactory lbClientFactory) {
+	public LoadBalancerFeignClient(Client delegate,
+			CachingSpringLoadBalancerFactory lbClientFactory) {
 		this.delegate = delegate;
 		this.lbClientFactory = lbClientFactory;
 	}
@@ -47,8 +48,8 @@ public class LoadBalancerFeignClient implements Client {
 			URI asUri = URI.create(request.url());
 			String clientName = asUri.getHost();
 			URI uriWithoutHost = cleanUrl(request.url(), clientName);
-			FeignLoadBalancer.RibbonRequest ribbonRequest = new FeignLoadBalancer.RibbonRequest(this.delegate,
-					request, uriWithoutHost);
+			FeignLoadBalancer.RibbonRequest ribbonRequest = new FeignLoadBalancer.RibbonRequest(
+					this.delegate, request, uriWithoutHost);
 			return lbClient(clientName).executeWithLoadBalancer(ribbonRequest,
 					new FeignOptionsClientConfig(options)).toResponse();
 		}