Support Multiple Clients Using The Same Service (#90)

* Use serviceId as url target if present.

Fixes gh-67

* Code review fixes and improvements

* Fix test

* Add contextId to override bean name of feign client and its configuration.

* Add documentation

* Add contextId example to documentation

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientBuilderTests.java

@@ -91,7 +91,7 @@ public class FeignClientBuilderTests {
 		// on this builder class.
 		// (2) Or a new field was added and the builder class has to be extended with this
 		// new field.
-		Assert.assertThat(methodNames, Matchers.contains("decode404", "fallback",
+		Assert.assertThat(methodNames, Matchers.contains("contextId", "decode404", "fallback",
 				"fallbackFactory", "name", "path", "url"));
 	}
 
@@ -105,6 +105,7 @@ public class FeignClientBuilderTests {
 		assertFactoryBeanField(builder, "applicationContext", applicationContext);
 		assertFactoryBeanField(builder, "type", FeignClientBuilderTests.class);
 		assertFactoryBeanField(builder, "name", "TestClient");
+		assertFactoryBeanField(builder, "contextId", "TestClient");
 
 		// and:
 		assertFactoryBeanField(builder, "url",

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignClientUsingPropertiesTests.java

@@ -81,15 +81,15 @@ public class FeignClientUsingPropertiesTests {
 
 	public FeignClientUsingPropertiesTests() {
 		fooFactoryBean = new FeignClientFactoryBean();
-		fooFactoryBean.setName("foo");
+		fooFactoryBean.setContextId("foo");
 		fooFactoryBean.setType(FeignClientFactoryBean.class);
 
 		barFactoryBean = new FeignClientFactoryBean();
-		barFactoryBean.setName("bar");
+		barFactoryBean.setContextId("bar");
 		barFactoryBean.setType(FeignClientFactoryBean.class);
 
 		formFactoryBean = new FeignClientFactoryBean();
-		formFactoryBean.setName("form");
+		formFactoryBean.setContextId("form");
 		formFactoryBean.setType(FeignClientFactoryBean.class);
 	}
 

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/SpringDecoderTests.java

@@ -62,6 +62,7 @@ public class SpringDecoderTests extends FeignClientFactoryBean {
 
 	public SpringDecoderTests() {
 		setName("test");
+		setContextId("test");
 	}
 
 	public TestClient testClient() {

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/invalid/FeignClientValidationTests.java

@@ -23,9 +23,13 @@ import feign.hystrix.HystrixFeign;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
+import org.springframework.cloud.client.loadbalancer.LoadBalancerAutoConfiguration;
+import org.springframework.cloud.commons.httpclient.HttpClientConfiguration;
+import org.springframework.cloud.netflix.ribbon.RibbonAutoConfiguration;
 import org.springframework.cloud.openfeign.EnableFeignClients;
 import org.springframework.cloud.openfeign.FeignAutoConfiguration;
 import org.springframework.cloud.openfeign.FeignClient;
+import org.springframework.cloud.openfeign.ribbon.FeignRibbonClientAutoConfiguration;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -64,24 +68,61 @@ public class FeignClientValidationTests {
 
 	@Test
 	public void testServiceIdAndValue() {
-		this.expected.expectMessage("only one is permitted");
 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
-				NameAndValueConfiguration.class);
+				LoadBalancerAutoConfiguration.class,
+				RibbonAutoConfiguration.class,
+				FeignRibbonClientAutoConfiguration.class,
+				NameAndServiceIdConfiguration.class);
 		assertNotNull(context.getBean(NameAndServiceIdConfiguration.Client.class));
 		context.close();
 	}
 
 	@Configuration
-	@Import(FeignAutoConfiguration.class)
+	@Import({FeignAutoConfiguration.class, HttpClientConfiguration.class})
 	@EnableFeignClients(clients = NameAndServiceIdConfiguration.Client.class)
 	protected static class NameAndServiceIdConfiguration {
 
-		@FeignClient(serviceId = "foo", name = "bar")
+		@FeignClient(name = "bar", serviceId = "foo")
 		interface Client {
 			@RequestMapping(method = RequestMethod.GET, value = "/")
 			String get();
 		}
+	}
 
+	@Test
+	public void testDuplicatedClientNames() {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		context.setAllowBeanDefinitionOverriding(false);
+		context.register(
+				LoadBalancerAutoConfiguration.class,
+				RibbonAutoConfiguration.class,
+				FeignRibbonClientAutoConfiguration.class,
+				DuplicatedFeignClientNamesConfiguration.class
+		);
+		context.refresh();
+		assertNotNull(context.getBean(DuplicatedFeignClientNamesConfiguration.FooClient.class));
+		assertNotNull(context.getBean(DuplicatedFeignClientNamesConfiguration.BarClient.class));
+		context.close();
+	}
+
+	@Configuration
+
+	@Import({FeignAutoConfiguration.class, HttpClientConfiguration.class})
+	@EnableFeignClients(clients = {DuplicatedFeignClientNamesConfiguration.FooClient.class,
+			DuplicatedFeignClientNamesConfiguration.BarClient.class})
+	protected static class DuplicatedFeignClientNamesConfiguration {
+
+		@FeignClient(contextId = "foo", name = "bar")
+		interface FooClient {
+			@RequestMapping(method = RequestMethod.GET, value = "/")
+			String get();
+		}
+
+		@FeignClient(name = "bar")
+		interface BarClient {
+			@RequestMapping(method = RequestMethod.GET, value = "/")
+			String get();
+		}
 	}
 
 	@Test