Fix RestClient to use defaultRequest on RestClient.Builder

spring-web/src/main/java/org/springframework/web/client/DefaultRestClient.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -71,6 +71,7 @@
  *
  * @author Arjen Poutsma
  * @author Sebastien Deleuze
+ * @author Injae Kim
  * @since 6.1
  * @see RestClient#create()
  * @see RestClient#create(String)
@@ -99,6 +100,9 @@ final class DefaultRestClient implements RestClient {
 	@Nullable
 	private final HttpHeaders defaultHeaders;
 
+	@Nullable
+	private final Consumer<RequestHeadersSpec<?>> defaultRequest;
+
 	private final List<StatusHandler> defaultStatusHandlers;
 
 	private final DefaultRestClientBuilder builder;
@@ -116,6 +120,7 @@ final class DefaultRestClient implements RestClient {
 			@Nullable List<ClientHttpRequestInitializer> initializers,
 			UriBuilderFactory uriBuilderFactory,
 			@Nullable HttpHeaders defaultHeaders,
+			@Nullable Consumer<RequestHeadersSpec<?>> defaultRequest,
 			@Nullable List<StatusHandler> statusHandlers,
 			List<HttpMessageConverter<?>> messageConverters,
 			ObservationRegistry observationRegistry,
@@ -127,6 +132,7 @@ final class DefaultRestClient implements RestClient {
 		this.interceptors = interceptors;
 		this.uriBuilderFactory = uriBuilderFactory;
 		this.defaultHeaders = defaultHeaders;
+		this.defaultRequest = defaultRequest;
 		this.defaultStatusHandlers = (statusHandlers != null ? new ArrayList<>(statusHandlers) : new ArrayList<>());
 		this.messageConverters = messageConverters;
 		this.observationRegistry = observationRegistry;
@@ -452,6 +458,9 @@ private <T> T exchangeInternal(ExchangeFunction<T> exchangeFunction, boolean clo
 			URI uri = null;
 			try {
 				uri = initUri();
+				if (defaultRequest != null) {
+					defaultRequest.accept(this);
+				}
 				HttpHeaders headers = initHeaders();
 				ClientHttpRequest clientRequest = createRequest(uri);
 				clientRequest.getHeaders().addAll(headers);

spring-web/src/main/java/org/springframework/web/client/DefaultRestClientBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -58,6 +58,7 @@
  * Default implementation of {@link RestClient.Builder}.
  *
  * @author Arjen Poutsma
+ * @author Injae Kim
  * @since 6.1
  */
 final class DefaultRestClientBuilder implements RestClient.Builder {
@@ -371,6 +372,7 @@ public RestClient build() {
 		return new DefaultRestClient(requestFactory,
 				this.interceptors, this.initializers, uriBuilderFactory,
 				defaultHeaders,
+				this.defaultRequest,
 				this.statusHandlers,
 				messageConverters,
 				this.observationRegistry,

spring-web/src/test/java/org/springframework/web/client/RestClientIntegrationTests.java

@@ -64,6 +64,7 @@
  *
  * @author Arjen Poutsma
  * @author Sebastien Deleuze
+ * @author Injae Kim
  */
 class RestClientIntegrationTests {
 
@@ -856,6 +857,35 @@ void filterForErrorHandling(ClientHttpRequestFactory requestFactory) {
 		expectRequestCount(2);
 	}
 
+	@ParameterizedRestClientTest
+	void defaultRequest(ClientHttpRequestFactory requestFactory) {
+		startServer(requestFactory);
+
+		prepareResponse(response ->
+				response.setHeader("Content-Type", "text/plain").setBody("Hello Spring!"));
+
+		String result = this.restClient.mutate()
+				.defaultRequest(spec -> spec
+						.header("X-Test-Header-Default", "testDefaultValue")
+						.header("X-Test-Header", "testDefaultValueShouldBeOverride"))
+				.build()
+				.get()
+				.uri("/greeting")
+				.header("X-Test-Header", "testHeaderValue")
+				.accept(MediaType.APPLICATION_JSON)
+				.retrieve()
+				.body(String.class);
+
+		assertThat(result).isEqualTo("Hello Spring!");
+
+		expectRequestCount(1);
+		expectRequest(request -> {
+			assertThat(request.getHeader("X-Test-Header-Default")).isEqualTo("testDefaultValue");
+			assertThat(request.getHeader("X-Test-Header")).isEqualTo("testHeaderValue");
+			assertThat(request.getHeader(HttpHeaders.ACCEPT)).isEqualTo("application/json");
+			assertThat(request.getPath()).isEqualTo("/greeting");
+		});
+	}
 
 	private void prepareResponse(Consumer<MockResponse> consumer) {
 		MockResponse response = new MockResponse();