Expose RestClientBuilder when RestHighLevelClient is not available

This commits exposes the RestClientBuilder as a bean even when the
RestHighLevelClient is not available. It allows users to create their
own RestClient beans using the Spring Boot configured RestClientBuilder
when they are not using the RestHighLevelClient.

Fixes gh-28655

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/elasticsearch/ElasticsearchRestClientAutoConfiguration.java

@@ -16,12 +16,10 @@
 
 package org.springframework.boot.autoconfigure.elasticsearch;
 
-import org.elasticsearch.client.RestClient;
-import org.elasticsearch.client.RestHighLevelClient;
+import org.elasticsearch.client.RestClientBuilder;
 
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchRestClientConfigurations.RestClientBuilderConfiguration;
 import org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchRestClientConfigurations.RestClientSnifferConfiguration;
 import org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchRestClientConfigurations.RestHighLevelClientConfiguration;
@@ -38,8 +36,7 @@ import org.springframework.context.annotation.Import;
  */
 @SuppressWarnings("deprecation")
 @Configuration(proxyBeanMethods = false)
-@ConditionalOnClass(RestHighLevelClient.class)
-@ConditionalOnMissingBean(RestClient.class)
+@ConditionalOnClass(RestClientBuilder.class)
 @EnableConfigurationProperties({ ElasticsearchProperties.class, ElasticsearchRestClientProperties.class,
 		DeprecatedElasticsearchRestClientProperties.class })
 @Import({ RestClientBuilderConfiguration.class, RestHighLevelClientConfiguration.class,

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/elasticsearch/ElasticsearchRestClientConfigurations.java

@@ -112,7 +112,8 @@ class ElasticsearchRestClientConfigurations {
 	}
 
 	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnMissingBean(RestHighLevelClient.class)
+	@ConditionalOnClass(RestHighLevelClient.class)
+	@ConditionalOnMissingBean({ RestHighLevelClient.class, RestClient.class })
 	static class RestHighLevelClientConfiguration {
 
 		@Bean

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/elasticsearch/ElasticsearchRestClientAutoConfigurationTests.java

@@ -55,6 +55,7 @@ import static org.mockito.Mockito.verifyNoInteractions;
  * @author Brian Clozel
  * @author Vedran Pavic
  * @author Evgeniy Cheban
+ * @author Filip Hrisafov
  */
 class ElasticsearchRestClientAutoConfigurationTests {
 
@@ -64,14 +65,22 @@ class ElasticsearchRestClientAutoConfigurationTests {
 	@Test
 	void configureShouldOnlyCreateHighLevelRestClient() {
 		this.contextRunner.run((context) -> assertThat(context).doesNotHaveBean(RestClient.class)
-				.hasSingleBean(RestHighLevelClient.class));
+				.hasSingleBean(RestClientBuilder.class).hasSingleBean(RestHighLevelClient.class));
+	}
+
+	@Test
+	void configureWithoutRestHighLevelClientShouldOnlyCreateRestClientBuilder() {
+		this.contextRunner.withClassLoader(new FilteredClassLoader(RestHighLevelClient.class))
+				.run((context) -> assertThat(context).doesNotHaveBean(RestClient.class)
+						.doesNotHaveBean(RestHighLevelClient.class).hasSingleBean(RestClientBuilder.class));
 	}
 
 	@Test
 	void configureWhenCustomRestClientShouldBackOff() {
-		this.contextRunner.withBean("customRestClient", RestClient.class, () -> mock(RestClient.class))
+		this.contextRunner.withUserConfiguration(CustomRestClientConfiguration.class)
 				.run((context) -> assertThat(context).doesNotHaveBean(RestHighLevelClient.class)
-						.hasSingleBean(RestClient.class).hasBean("customRestClient"));
+						.hasSingleBean(RestClientBuilder.class).hasSingleBean(RestClient.class)
+						.hasBean("customRestClient"));
 	}
 
 	@Test
@@ -304,6 +313,16 @@ class ElasticsearchRestClientAutoConfigurationTests {
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	static class CustomRestClientConfiguration {
+
+		@Bean
+		RestClient customRestClient(RestClientBuilder builder) {
+			return builder.build();
+		}
+
+	}
+
 	@ParameterizedTest
 	@Target(ElementType.METHOD)
 	@Retention(RetentionPolicy.RUNTIME)