Fix merging default headers and params. Fixes gh-1001.

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 the original author or authors.
+ * Copyright 2013-2024 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.
@@ -324,19 +324,26 @@ public class FeignClientFactoryBean
 
 	protected void configureDefaultRequestElements(FeignClientProperties.FeignClientConfiguration defaultConfig,
 			FeignClientProperties.FeignClientConfiguration clientConfig, Feign.Builder builder) {
-		Map<String, Collection<String>> defaultRequestHeaders = defaultConfig != null
-				? defaultConfig.getDefaultRequestHeaders() : new HashMap<>();
+		Map<String, Collection<String>> defaultRequestHeaders = new HashMap<>();
+		if (defaultConfig != null) {
+			defaultConfig.getDefaultRequestHeaders()
+					.forEach((k, v) -> defaultRequestHeaders.put(k, new ArrayList<>(v)));
+		}
 		if (clientConfig != null) {
-			defaultRequestHeaders.putAll(clientConfig.getDefaultRequestHeaders());
+			clientConfig.getDefaultRequestHeaders().forEach((k, v) -> defaultRequestHeaders.put(k, new ArrayList<>(v)));
 		}
 		if (!defaultRequestHeaders.isEmpty()) {
 			addDefaultRequestHeaders(defaultRequestHeaders, builder);
 		}
 
-		Map<String, Collection<String>> defaultQueryParameters = defaultConfig != null
-				? defaultConfig.getDefaultQueryParameters() : new HashMap<>();
+		Map<String, Collection<String>> defaultQueryParameters = new HashMap<>();
+		if (defaultConfig != null) {
+			defaultConfig.getDefaultQueryParameters()
+					.forEach((k, v) -> defaultQueryParameters.put(k, new ArrayList<>(v)));
+		}
 		if (clientConfig != null) {
-			defaultQueryParameters.putAll(clientConfig.getDefaultQueryParameters());
+			clientConfig.getDefaultQueryParameters()
+					.forEach((k, v) -> defaultQueryParameters.put(k, new ArrayList<>(v)));
 		}
 		if (!defaultQueryParameters.isEmpty()) {
 			addDefaultQueryParams(defaultQueryParameters, builder);

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

@@ -0,0 +1,156 @@
+/*
+ * Copyright 2013-2024 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;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.web.server.LocalServerPort;
+import org.springframework.cloud.client.DefaultServiceInstance;
+import org.springframework.cloud.loadbalancer.annotation.LoadBalancerClient;
+import org.springframework.cloud.loadbalancer.annotation.LoadBalancerClients;
+import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
+import org.springframework.cloud.loadbalancer.support.ServiceInstanceListSuppliers;
+import org.springframework.cloud.openfeign.test.NoSecurityConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Import;
+import org.springframework.http.HttpHeaders;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestHeader;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+import static java.util.Map.entry;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.http.MediaType.APPLICATION_JSON_VALUE;
+
+/**
+ * Integration tests for {@link FeignClientFactoryBean}.
+ *
+ * @author Olga Maciaszek-Sharma
+ */
+@SpringBootTest(classes = FeignClientFactoryBeanIntegrationTests.Application.class,
+	webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+@ActiveProfiles("defaultstest")
+class FeignClientFactoryBeanIntegrationTests {
+
+	@Autowired
+	TestClientA testClientA;
+
+	@Autowired
+	TestClientB testClientB;
+
+	@Test
+	void shouldProcessDefaultRequestHeadersPerClient() {
+		assertThat(testClientA.headers()).isNotNull()
+			.contains(entry("x-custom-header-2", List.of("2 from default")),
+				entry("x-custom-header", List.of("from client A")));
+		assertThat(testClientB.headers()).isNotNull()
+			.contains(entry("x-custom-header-2", List.of("2 from default")),
+				entry("x-custom-header", List.of("from client B")));
+	}
+
+	@Test
+	void shouldProcessDefaultQueryParamsPerClient() {
+		assertThat(testClientA.params()).isNotNull()
+			.contains(entry("customParam2", "2 from default"),
+				entry("customParam1", "from client A"));
+		assertThat(testClientB.params()).isNotNull()
+			.contains(entry("customParam2", "2 from default"),
+				entry("customParam1", "from client B"));
+	}
+
+	@FeignClient("testClientA")
+	public interface TestClientA {
+
+		@GetMapping("/headers")
+		Map<String, List<String>> headers();
+
+		@GetMapping("/params")
+		Map<String, String> params();
+
+	}
+
+	@FeignClient("testClientB")
+	public interface TestClientB {
+
+		@GetMapping("/headers")
+		Map<String, List<String>> headers();
+
+		@GetMapping("/params")
+		Map<String, String> params();
+
+	}
+
+	@EnableAutoConfiguration
+	@EnableFeignClients(clients = {TestClientA.class, TestClientB.class})
+	@RestController
+	@LoadBalancerClients({@LoadBalancerClient(name = "testClientA", configuration = TestClientAConfiguration.class),
+		@LoadBalancerClient(name = "testClientB", configuration = TestClientBConfiguration.class)})
+	@RequestMapping
+	@Import(NoSecurityConfiguration.class)
+	protected static class Application {
+
+		@GetMapping(value = "/headers", produces = APPLICATION_JSON_VALUE)
+		public Map<String, List<String>> headers(@RequestHeader HttpHeaders headers) {
+			return new HashMap<>(headers);
+		}
+
+		@GetMapping(value = "/params", produces = APPLICATION_JSON_VALUE)
+		public Map<String, String> headersB(@RequestParam Map<String, String> params) {
+			return params;
+		}
+
+	}
+
+	// LoadBalancer with fixed server list for "testClientA" pointing to localhost
+	static class TestClientAConfiguration {
+
+		@LocalServerPort
+		private int port = 0;
+
+		@Bean
+		public ServiceInstanceListSupplier testClientAServiceInstanceListSupplier() {
+			return ServiceInstanceListSuppliers.from("testClientA",
+				new DefaultServiceInstance("local-1", "testClientA", "localhost", port, false));
+		}
+
+	}
+
+	// LoadBalancer with fixed server list for "testClientB" pointing to localhost
+	static class TestClientBConfiguration {
+
+		@LocalServerPort
+		private int port = 0;
+
+		@Bean
+		public ServiceInstanceListSupplier testClientBServiceInstanceListSupplier() {
+			return ServiceInstanceListSuppliers.from("testClientB",
+				new DefaultServiceInstance("local-1", "testClientB", "localhost", port, false));
+		}
+
+	}
+
+}

spring-cloud-openfeign-core/src/test/resources/application-defaultstest.yml

@@ -0,0 +1,31 @@
+spring:
+  cloud:
+    openfeign:
+      client:
+        config:
+          default:
+            logger-level: FULL
+            default-request-headers:
+              x-custom-header:
+                - "default"
+              x-custom-header-2:
+                - "2 from default"
+            default-query-parameters:
+              customParam1:
+                - "default"
+              customParam2:
+                - "2 from default"
+          testClientA:
+            default-request-headers:
+              x-custom-header:
+                - "from client A"
+            default-query-parameters:
+              customParam1:
+                - "from client A"
+          testClientB:
+            default-request-headers:
+              x-custom-header:
+                - "from client B"
+            default-query-parameters:
+              customParam1:
+                - "from client B"