Align HttpClient defaults with Spring Framework and provide an opt-out

Update default for `ReactorClientHttpRequestFactoryBuilder` and
`ReactorClientHttpConnectorBuilder` to align with Spring Framework.

Also provide method of opting out in case proxyWithSystemProperties is
not wanted.

Closes gh-49950

module/spring-boot-http-client/src/main/java/org/springframework/boot/http/client/ReactorClientHttpRequestFactoryBuilder.java

@@ -96,6 +96,29 @@ public final class ReactorClientHttpRequestFactoryBuilder
 				this.httpClientBuilder.withHttpClientFactory(factory));
 	}
 
+	/**
+	 * Return a new {@link ReactorClientHttpRequestFactoryBuilder} that does not apply any
+	 * defaults when first creating the {@link HttpClient}.
+	 * @return a new {@link ReactorClientHttpRequestFactoryBuilder} instance
+	 * @since 4.1.0
+	 */
+	public ReactorClientHttpRequestFactoryBuilder withoutHttpClientDefaults() {
+		return withHttpClientDefaults(null);
+	}
+
+	/**
+	 * Return a new {@link ReactorClientHttpRequestFactoryBuilder} that applies the given
+	 * factory defaults when first creating the {@link HttpClient}.
+	 * @param factoryDefaults the factory to use
+	 * @return a new {@link ReactorClientHttpRequestFactoryBuilder} instance
+	 * @since 4.1.0
+	 */
+	public ReactorClientHttpRequestFactoryBuilder withHttpClientDefaults(
+			@Nullable UnaryOperator<HttpClient> factoryDefaults) {
+		return new ReactorClientHttpRequestFactoryBuilder(getCustomizers(),
+				this.httpClientBuilder.withHttpClientDefaults(factoryDefaults));
+	}
+
 	/**
 	 * Return a new {@link ReactorClientHttpRequestFactoryBuilder} that applies additional
 	 * customization to the underlying {@link HttpClient}.

module/spring-boot-http-client/src/main/java/org/springframework/boot/http/client/ReactorHttpClientBuilder.java

@@ -50,17 +50,21 @@ public final class ReactorHttpClientBuilder {
 
 	private final Supplier<HttpClient> factory;
 
+	private final UnaryOperator<HttpClient> factoryDefaults;
+
 	private final UnaryOperator<HttpClient> customizer;
 
 	private final @Nullable ResolvedAddressSelector<? super HttpClientConfig> resolvedAddressSelector;
 
 	public ReactorHttpClientBuilder() {
-		this(HttpClient::create, UnaryOperator.identity(), null);
+		this(HttpClient::create, ReactorHttpClientBuilder::applySpringDefaults, UnaryOperator.identity(), null);
 	}
 
-	private ReactorHttpClientBuilder(Supplier<HttpClient> httpClientFactory, UnaryOperator<HttpClient> customizer,
+	private ReactorHttpClientBuilder(Supplier<HttpClient> factory, UnaryOperator<HttpClient> factoryDefaults,
+			UnaryOperator<HttpClient> customizer,
 			@Nullable ResolvedAddressSelector<? super HttpClientConfig> resolvedAddressSelector) {
-		this.factory = httpClientFactory;
+		this.factory = factory;
+		this.factoryDefaults = factoryDefaults;
 		this.customizer = customizer;
 		this.resolvedAddressSelector = resolvedAddressSelector;
 	}
@@ -74,6 +78,7 @@ public final class ReactorHttpClientBuilder {
 	public ReactorHttpClientBuilder withReactorResourceFactory(ReactorResourceFactory reactorResourceFactory) {
 		Assert.notNull(reactorResourceFactory, "'reactorResourceFactory' must not be null");
 		return new ReactorHttpClientBuilder(() -> HttpClient.create(reactorResourceFactory.getConnectionProvider()),
+				this.factoryDefaults,
 				(httpClient) -> this.customizer.apply(httpClient).runOn(reactorResourceFactory.getLoopResources()),
 				this.resolvedAddressSelector);
 	}
@@ -86,7 +91,31 @@ public final class ReactorHttpClientBuilder {
 	 */
 	public ReactorHttpClientBuilder withHttpClientFactory(Supplier<HttpClient> factory) {
 		Assert.notNull(factory, "'factory' must not be null");
-		return new ReactorHttpClientBuilder(factory, this.customizer, this.resolvedAddressSelector);
+		return new ReactorHttpClientBuilder(factory, this.factoryDefaults, this.customizer,
+				this.resolvedAddressSelector);
+	}
+
+	/**
+	 * Return a new {@link ReactorHttpClientBuilder} that does not apply any defaults when
+	 * first creating the {@link HttpClient}.
+	 * @return a new {@link ReactorHttpClientBuilder} instance
+	 * @since 4.1.0
+	 */
+	public ReactorHttpClientBuilder withoutHttpClientDefaults() {
+		return withHttpClientDefaults(null);
+	}
+
+	/**
+	 * Return a new {@link ReactorHttpClientBuilder} that applies the given factory
+	 * defaults when first creating the {@link HttpClient}.
+	 * @param factoryDefaults the factory to use
+	 * @return a new {@link ReactorHttpClientBuilder} instance
+	 * @since 4.1.0
+	 */
+	public ReactorHttpClientBuilder withHttpClientDefaults(@Nullable UnaryOperator<HttpClient> factoryDefaults) {
+		return new ReactorHttpClientBuilder(this.factory,
+				(factoryDefaults != null) ? factoryDefaults : UnaryOperator.identity(), this.customizer,
+				this.resolvedAddressSelector);
 	}
 
 	/**
@@ -97,7 +126,7 @@ public final class ReactorHttpClientBuilder {
 	 */
 	public ReactorHttpClientBuilder withHttpClientCustomizer(UnaryOperator<HttpClient> customizer) {
 		Assert.notNull(customizer, "'customizer' must not be null");
-		return new ReactorHttpClientBuilder(this.factory,
+		return new ReactorHttpClientBuilder(this.factory, this.factoryDefaults,
 				(httpClient) -> customizer.apply(this.customizer.apply(httpClient)), this.resolvedAddressSelector);
 	}
 
@@ -112,7 +141,8 @@ public final class ReactorHttpClientBuilder {
 	public ReactorHttpClientBuilder withResolvedAddressSelector(
 			ResolvedAddressSelector<? super HttpClientConfig> resolvedAddressSelector) {
 		Assert.notNull(resolvedAddressSelector, "'resolvedAddressSelector' must not be null");
-		return new ReactorHttpClientBuilder(this.factory, this.customizer, resolvedAddressSelector);
+		return new ReactorHttpClientBuilder(this.factory, this.factoryDefaults, this.customizer,
+				resolvedAddressSelector);
 	}
 
 	/**
@@ -122,7 +152,7 @@ public final class ReactorHttpClientBuilder {
 	 */
 	public HttpClient build(@Nullable HttpClientSettings settings) {
 		settings = (settings != null) ? settings : HttpClientSettings.defaults();
-		HttpClient httpClient = applyDefaults(this.factory.get());
+		HttpClient httpClient = this.factoryDefaults.apply(this.factory.get());
 		PropertyMapper map = PropertyMapper.get();
 		httpClient = map.from(settings::connectTimeout).to(httpClient, this::setConnectTimeout);
 		httpClient = map.from(settings::readTimeout).to(httpClient, HttpClient::responseTimeout);
@@ -146,11 +176,6 @@ public final class ReactorHttpClientBuilder {
 				: this.resolvedAddressSelector;
 	}
 
-	HttpClient applyDefaults(HttpClient httpClient) {
-		// Aligns with Spring Framework defaults
-		return httpClient.compress(true);
-	}
-
 	private HttpClient setConnectTimeout(HttpClient httpClient, Duration timeout) {
 		return httpClient.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, (int) timeout.toMillis());
 	}
@@ -177,4 +202,9 @@ public final class ReactorHttpClientBuilder {
 		spec.sslContext(builder.build());
 	}
 
+	static HttpClient applySpringDefaults(HttpClient httpClient) {
+		// Aligns with Spring Framework defaults in ReactorClientHttpRequestFactory
+		return httpClient.compress(true).proxyWithSystemProperties();
+	}
+
 }

module/spring-boot-http-client/src/main/java/org/springframework/boot/http/client/reactive/ReactorClientHttpConnectorBuilder.java

@@ -90,6 +90,29 @@ public final class ReactorClientHttpConnectorBuilder
 				this.httpClientBuilder.withHttpClientFactory(factory));
 	}
 
+	/**
+	 * Return a new {@link ReactorClientHttpConnectorBuilder} that does not apply any
+	 * defaults when first creating the {@link HttpClient}.
+	 * @return a new {@link ReactorClientHttpConnectorBuilder} instance
+	 * @since 4.1.0
+	 */
+	public ReactorClientHttpConnectorBuilder withoutHttpClientDefaults() {
+		return withHttpClientDefaults(null);
+	}
+
+	/**
+	 * Return a new {@link ReactorClientHttpConnectorBuilder} that applies the given
+	 * factory defaults when first creating the {@link HttpClient}.
+	 * @param factoryDefaults the factory to use
+	 * @return a new {@link ReactorClientHttpConnectorBuilder} instance
+	 * @since 4.1.0
+	 */
+	public ReactorClientHttpConnectorBuilder withHttpClientDefaults(
+			@Nullable UnaryOperator<HttpClient> factoryDefaults) {
+		return new ReactorClientHttpConnectorBuilder(getCustomizers(),
+				this.httpClientBuilder.withHttpClientDefaults(factoryDefaults));
+	}
+
 	/**
 	 * Return a new {@link ReactorClientHttpConnectorBuilder} that applies additional
 	 * customization to the underlying {@link HttpClient}.

module/spring-boot-http-client/src/test/java/org/springframework/boot/http/client/ReactorClientHttpRequestFactoryBuilderTests.java

@@ -28,6 +28,7 @@ import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.EnumSource;
 import reactor.netty.http.client.HttpClient;
 
+import org.springframework.http.client.ClientHttpRequestFactory;
 import org.springframework.http.client.ReactorClientHttpRequestFactory;
 import org.springframework.http.client.ReactorResourceFactory;
 import org.springframework.test.util.ReflectionTestUtils;
@@ -63,6 +64,29 @@ class ReactorClientHttpRequestFactoryBuilderTests
 		assertThat(called).containsExactly(true);
 	}
 
+	@Test
+	void springHttpClientDefaults() {
+		ClientHttpRequestFactory factory = ClientHttpRequestFactoryBuilder.reactor().build();
+		assertThat(factory).extracting("httpClient.config.acceptGzip").isEqualTo(true);
+	}
+
+	@Test
+	void withoutHttpClientDefaults() {
+		ClientHttpRequestFactory factory = ClientHttpRequestFactoryBuilder.reactor()
+			.withoutHttpClientDefaults()
+			.build();
+		assertThat(factory).extracting("httpClient.config.acceptGzip").isEqualTo(false);
+	}
+
+	@Test
+	void withHttpClientDefaults() {
+		ClientHttpRequestFactory factory = ClientHttpRequestFactoryBuilder.reactor()
+			.withHttpClientDefaults((httpClient) -> httpClient.baseUrl("test"))
+			.build();
+		assertThat(factory).extracting("httpClient.config.acceptGzip").isEqualTo(false);
+		assertThat(factory).extracting("httpClient.config.baseUrl").isEqualTo("test");
+	}
+
 	@Test
 	void withReactorResourceFactory() {
 		ReactorResourceFactory resourceFactory = spy(new ReactorResourceFactory());

module/spring-boot-http-client/src/test/java/org/springframework/boot/http/client/reactive/ReactorClientHttpConnectorBuilderTests.java

@@ -64,6 +64,27 @@ class ReactorClientHttpConnectorBuilderTests
 		assertThat(called).containsExactly(true);
 	}
 
+	@Test
+	void springHttpClientDefaults() {
+		ReactorClientHttpConnector connector = ClientHttpConnectorBuilder.reactor().build();
+		assertThat(connector).extracting("httpClient.config.acceptGzip").isEqualTo(true);
+	}
+
+	@Test
+	void withoutHttpClientDefaults() {
+		ReactorClientHttpConnector connector = ClientHttpConnectorBuilder.reactor().withoutHttpClientDefaults().build();
+		assertThat(connector).extracting("httpClient.config.acceptGzip").isEqualTo(false);
+	}
+
+	@Test
+	void withHttpClientDefaults() {
+		ReactorClientHttpConnector connector = ClientHttpConnectorBuilder.reactor()
+			.withHttpClientDefaults((httpClient) -> httpClient.baseUrl("test"))
+			.build();
+		assertThat(connector).extracting("httpClient.config.acceptGzip").isEqualTo(false);
+		assertThat(connector).extracting("httpClient.config.baseUrl").isEqualTo("test");
+	}
+
 	@Test
 	void withReactorResourceFactory() {
 		ReactorResourceFactory resourceFactory = spy(new ReactorResourceFactory());