Allow RestTemplateBuilder to be further customized

Closes gh-23389

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/web/client/RestTemplateBuilderCustomizationExample.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2020 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.boot.docs.web.client;
+
+import java.time.Duration;
+
+import org.springframework.boot.autoconfigure.web.client.RestTemplateBuilderConfigurer;
+import org.springframework.boot.web.client.RestTemplateBuilder;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Example configuration for using a {@link RestTemplateBuilderConfigurer} to configure a
+ * custom {@link RestTemplateBuilder}.
+ *
+ * @author Stephane Nicoll
+ */
+@Configuration(proxyBeanMethods = false)
+public class RestTemplateBuilderCustomizationExample {
+
+	// tag::customizer[]
+	@Bean
+	public RestTemplateBuilder restTemplateBuilder(RestTemplateBuilderConfigurer configurer) {
+		return configurer.configure(new RestTemplateBuilder()).setConnectTimeout(Duration.ofSeconds(5))
+				.setReadTimeout(Duration.ofSeconds(2));
+	}
+	// end::customizer[]
+
+}