Fix for @EnableFeignClients(clients) scans classes in nested packages (#422)

* Test to verify sub level client error

Error is described in https://github.com/spring-cloud/spring-cloud-openfeign/issues/331

Application fails when one Feign client is `org.TopClient` and second is in subpackage:  `org.sub.SubClient`

The error reason is that `SubClient` is registered twice

* Fix for @EnableFeignClients(clients) scans classes in nested packages twice

https://github.com/spring-cloud/spring-cloud-openfeign/issues/331
(cherry picked from commit fe62b0db9002052a72e5bbb9fdc5458993c16951)

# Conflicts:
#	spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientsRegistrar.java

* delete unused code

(cherry picked from commit 4df865d1d64fc0a9b5e37ea4c6466a0dbe485141)

* add file header

* Apply review

Co-authored-by: michal <michal@michal-desktop>

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

@@ -20,7 +20,9 @@ import java.util.Collections;
 
 import org.junit.Test;
 
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.cloud.openfeign.test.TestAutoConfiguration;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.mock.env.MockEnvironment;
@@ -28,10 +30,12 @@ import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
 
 /**
  * @author Spencer Gibb
  * @author Gang Li
+ * @author Michal Domagala
  */
 public class FeignClientsRegistrarTests {
 
@@ -89,6 +93,17 @@ public class FeignClientsRegistrarTests {
 		new AnnotationConfigApplicationContext(FallbackFactoryTestConfig.class);
 	}
 
+	@Test
+	public void shouldPassSubLevelFeignClient() {
+		AnnotationConfigApplicationContext config = new AnnotationConfigApplicationContext();
+		((DefaultListableBeanFactory) config.getBeanFactory()).setAllowBeanDefinitionOverriding(false);
+		config.register(TopLevelSubLevelTestConfig.class);
+		assertThatCode(() -> config.refresh())
+			.as("Case https://github.com/spring-cloud/spring-cloud-openfeign/issues/331 should be solved")
+			.doesNotThrowAnyException();
+
+	}
+
 	@FeignClient(name = "fallbackTestClient", url = "http://localhost:8080/",
 			fallback = FallbackClient.class)
 	protected interface FallbackClient {
@@ -122,4 +137,11 @@ public class FeignClientsRegistrarTests {
 
 	}
 
+	@EnableFeignClients(clients = {
+		org.springframework.cloud.openfeign.feignclientsregistrar.TopLevelClient.class,
+		org.springframework.cloud.openfeign.feignclientsregistrar.sub.SubLevelClient.class})
+	@EnableAutoConfiguration(exclude = TestAutoConfiguration.class)
+	protected static class TopLevelSubLevelTestConfig {
+	}
+
 }

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

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2013-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.openfeign.feignclientsregistrar;
+
+import org.springframework.cloud.openfeign.FeignClient;
+
+/**
+ * @author Michal Domagala
+ */
+
+@FeignClient("top-level")
+public interface TopLevelClient {
+}

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/feignclientsregistrar/sub/SubLevelClient.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2013-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.openfeign.feignclientsregistrar.sub;
+
+import org.springframework.cloud.openfeign.FeignClient;
+
+/**
+ * @author Michal Domagala
+ */
+
+@FeignClient("sub-level")
+public interface SubLevelClient {
+}