RestClient supports supplier settings requestFactory.

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

@@ -25,6 +25,7 @@
 import java.util.Map;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
 
 import io.micrometer.observation.ObservationRegistry;
 
@@ -387,6 +388,12 @@ public RestClient.Builder requestFactory(ClientHttpRequestFactory requestFactory
 		return this;
 	}
 
+	@Override
+	public RestClient.Builder requestFactory(Supplier<ClientHttpRequestFactory> requestFactorySupplier) {
+		this.requestFactory = requestFactorySupplier.get();
+		return this;
+	}
+
 	@Override
 	public RestClient.Builder messageConverters(Consumer<List<HttpMessageConverter<?>>> configurer) {
 		configurer.accept(initMessageConverters());

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

@@ -26,6 +26,7 @@
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
 
 import io.micrometer.observation.ObservationRegistry;
 
@@ -417,6 +418,23 @@ Builder defaultStatusHandler(Predicate<HttpStatusCode> statusPredicate,
 		 */
 		Builder requestFactory(ClientHttpRequestFactory requestFactory);
 
+		/**
+		 * Configure the {@link ClientHttpRequestFactory} to use. This is useful
+		 * for plugging in and/or customizing options of the underlying HTTP
+		 * client library (for example, SSL).
+		 * <p>If no request factory is specified, {@code RestClient} uses
+		 * {@linkplain org.springframework.http.client.HttpComponentsClientHttpRequestFactory Apache Http Client},
+		 * {@linkplain org.springframework.http.client.JettyClientHttpRequestFactory Jetty Http Client}
+		 * if available on the classpath, and defaults to the
+		 * {@linkplain org.springframework.http.client.JdkClientHttpRequestFactory JDK HttpClient}
+		 * if the {@code java.net.http} module is loaded, or to a
+		 * {@linkplain org.springframework.http.client.SimpleClientHttpRequestFactory simple default}
+		 * otherwise.
+		 * @param requestFactorySupplier the supplier for the request factory to use
+		 * @return this builder
+		 */
+		Builder requestFactory(Supplier<ClientHttpRequestFactory> requestFactorySupplier);
+
 		/**
 		 * Configure the message converters for the {@code RestClient} to use.
 		 * @param configurer the configurer to apply on the list of default

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

@@ -28,6 +28,7 @@
 
 import org.springframework.http.client.ClientHttpRequestInitializer;
 import org.springframework.http.client.ClientHttpRequestInterceptor;
+import org.springframework.http.client.JdkClientHttpRequestFactory;
 import org.springframework.http.client.JettyClientHttpRequestFactory;
 import org.springframework.http.client.support.BasicAuthenticationInterceptor;
 import org.springframework.http.converter.HttpMessageConverter;
@@ -283,4 +284,13 @@ private static Object fieldValue(String name, RestClient instance) {
 			return null;
 		}
 	}
+
+	@Test
+	void requestFactorySupplier() {
+		RestClient.Builder builder = RestClient.builder(new RestTemplate());
+		builder.requestFactory(() -> new JdkClientHttpRequestFactory());
+		DefaultRestClientBuilder defaultBuilder = (DefaultRestClientBuilder) builder;
+		assertThat(fieldValue("requestFactory", defaultBuilder)).isInstanceOf(JdkClientHttpRequestFactory.class);
+	}
+
 }