Only add default query params and default headers if not already in template. Fixes gh-590.

Author: OlgaMaciaszek

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

@@ -17,6 +17,7 @@
 package org.springframework.cloud.openfeign;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -276,13 +277,8 @@ protected void configureUsingProperties(FeignClientProperties.FeignClientConfigu
 			builder.encoder(getOrInstantiate(config.getEncoder()));
 		}
 
-		if (Objects.nonNull(config.getDefaultRequestHeaders())) {
-			builder.requestInterceptor(requestTemplate -> requestTemplate.headers(config.getDefaultRequestHeaders()));
-		}
-
-		if (Objects.nonNull(config.getDefaultQueryParameters())) {
-			builder.requestInterceptor(requestTemplate -> requestTemplate.queries(config.getDefaultQueryParameters()));
-		}
+		addDefaultRequestHeaders(config, builder);
+		addDefaultQueryParams(config, builder);
 
 		if (Objects.nonNull(config.getDecoder())) {
 			builder.decoder(getOrInstantiate(config.getDecoder()));
@@ -301,6 +297,35 @@ protected void configureUsingProperties(FeignClientProperties.FeignClientConfigu
 		}
 	}
 
+	private void addDefaultQueryParams(FeignClientProperties.FeignClientConfiguration config, Feign.Builder builder) {
+		Map<String, Collection<String>> defaultQueryParameters = config.getDefaultQueryParameters();
+		if (Objects.nonNull(defaultQueryParameters)) {
+			builder.requestInterceptor(requestTemplate -> {
+				Map<String, Collection<String>> queries = requestTemplate.queries();
+				defaultQueryParameters.keySet().forEach(key -> {
+					if (!queries.containsKey(key)) {
+						requestTemplate.query(key, defaultQueryParameters.get(key));
+					}
+				});
+			});
+		}
+	}
+
+	private void addDefaultRequestHeaders(FeignClientProperties.FeignClientConfiguration config,
+			Feign.Builder builder) {
+		Map<String, Collection<String>> defaultRequestHeaders = config.getDefaultRequestHeaders();
+		if (Objects.nonNull(defaultRequestHeaders)) {
+			builder.requestInterceptor(requestTemplate -> {
+				Map<String, Collection<String>> headers = requestTemplate.headers();
+				defaultRequestHeaders.keySet().forEach(key -> {
+					if (!headers.containsKey(key)) {
+						requestTemplate.header(key, defaultRequestHeaders.get(key));
+					}
+				});
+			});
+		}
+	}
+
 	private <T> T getOrInstantiate(Class<T> tClass) {
 		try {
 			return beanFactory != null ? beanFactory.getBean(tClass) : applicationContext.getBean(tClass);