Remove deprecated code.

Original Pull Request #2564
Closes #2563

Author: sothawo

CONTRIBUTING.adoc

@@ -8,7 +8,3 @@ Do not submit a Pull Request before having created an issue and having discussed
 == Running the test locally
 
 In order to run the tests locally with `./mvnw test` you need to have docker running because Spring Data Elasticsearch uses https://www.testcontainers.org/[Testcontainers] to start a local running Elasticsearch instance.
-
-== Class names of the test classes
-
-Test classes that do depend on the client have either `ERHLC` (when using the deprecated Elasticsearch  `RestHighLevelClient`) or `ELC` (the new `ElasticsearchClient`) in their name.

README.adoc

@@ -5,42 +5,20 @@ image:https://spring.io/badges/spring-data-elasticsearch/ga.svg[Spring Data Elas
 The primary goal of the https://projects.spring.io/spring-data[Spring Data] project is to make it easier to build Spring-powered applications that use new data access technologies such as non-relational databases, map-reduce frameworks, and cloud based data services.
 
 The Spring Data Elasticsearch project provides integration with the https://www.elastic.co/[Elasticsearch] search engine.
-Key functional areas of Spring Data Elasticsearch are a POJO centric model for interacting with a Elasticsearch Documents and easily writing a Repository style data access layer.
+Key functional areas of Spring Data Elasticsearch are a POJO centric model for interacting with Elasticsearch Documents and easily writing a Repository style data access layer.
 
 This project is lead and maintained by the community.
 
 == Features
 
-* Spring configuration support using Java based `@Configuration` classes or an XML namespace for a ES clients instances.
+* Spring configuration support using Java based `@Configuration` classes or an XML namespace for an ES client instances.
 * `ElasticsearchOperations` class and implementations that increases productivity performing common ES operations.
 Includes integrated object mapping between documents and POJOs.
 * Feature Rich Object Mapping integrated with Spring’s Conversion Service
 * Annotation based mapping metadata
 * Automatic implementation of `Repository` interfaces including support for custom search methods.
 * CDI support for repositories
 
-== About Elasticsearch versions and clients
-
-=== Elasticsearch 7.17 client libraries
-
-At the end of 2021 Elasticsearch with version 7.17 released the new version of their Java client and deprecated the `RestHighLevelCLient` which was the default way to access Elasticsearch up to then.
-
-Spring Data Elasticsearch will in version 4.4 offer the possibility to optionally use the new client as an alternative to the existing setup using the `RestHighLevelCLient`.
-The default client that is used still is the `RestHighLevelCLient`, first because the integration of the new client is not yet complete, the new client still has features missing and bugs which will hopefully be resolved soon.
-Second, and more important, the new Elasticsearch client forces users to switch from using `javax.json.spi.JsonProvider` to `jakarta.json.spi.JsonProvider`.
-Spring Data Elasticsearch cannot enforce this switch; Spring Boot will switch to `jakarta` with version 3 and then it's safe for Spring Data Elasticsearch to switch to the new client.
-
-So for version 4.4 Spring Data Elasticsearch will keep using the `RestHighLevelCLient` in version 7.17.x (as long as this will be available).
-
-=== Elasticsearch 8 client libraries
-
-In Elasticsearch 8, the `RestHighLevelCLient` has been removed.
-This means that a switch to this client version can only be done with the next major upgrade which will be Spring Data Elasticsearch 5, based on Spring Data 3, used by Spring Boot 3, based on Spring 6 and Java 17.
-
-=== Elasticsearch 8 cluster
-
-It should be possible to use the Elasticsearch 7 client to access a cluster running version 8 by setting the appropriate compatibility headers (see the documentation at https://docs.spring.io/spring-data/elasticsearch/docs/current/reference/html/#elasticsearch.clients.configuration). but I encountered and heard of cases where the response from the server is not parseable by the client although the headers are set, so use with care.
-
 == Code of Conduct
 
 This project is governed by the https://github.com/spring-projects/.github/blob/e3cc2ff230d8f1dca06535aa6b5a4a23815861d4/CODE_OF_CONDUCT.md[Spring Code of Conduct].
@@ -86,25 +64,7 @@ public class MyService {
 
 === Using the RestClient
 
-Provide a configuration like this:
-
-[source,java]
-----
-@Configuration
-public class RestClientConfig extends AbstractElasticsearchConfiguration {
-
-    @Override
-    @Bean
-    public RestHighLevelClient elasticsearchClient() {
-
-        final ClientConfiguration clientConfiguration = ClientConfiguration.builder()
-            .connectedTo("localhost:9200")
-            .build();
-
-        return RestClients.create(clientConfiguration).rest();
-    }
-}
-----
+Please check the [official documentation](https://docs.spring.io/spring-data/elasticsearch/docs/current/reference/html/#elasticsearch.clients.configuration).
 
 === Maven configuration
 
@@ -119,9 +79,6 @@ Add the Maven dependency:
 </dependency>
 ----
 
-// NOTE: since Github does not support include directives, the content of
-// the src/main/asciidoc/reference/preface.adoc file is duplicated here
-// Always change both files!
 **Compatibility Matrix**
 
 The compatibility between Spring Data Elasticsearch, Elasticsearch client drivers and Spring Boot versions can be found in the https://docs.spring.io/spring-data/elasticsearch/docs/current/reference/html/#preface.versions[reference documentation].

src/main/asciidoc/reference/elasticsearch-clients.adoc

@@ -105,98 +105,6 @@ This is a reactive implementation based on the Elasticsearch client implementati
 Basically one should just use the `ReactiveElasticsearchOperations` to interact with the Elasticsearch cluster.
 When using repositories, this instance is used under the hood as well.
 
-[[elasticsearch.clients.resthighlevelclient]]
-== High Level REST Client (deprecated)
-
-[CAUTION]
-====
-The Elasticsearch Java RestHighLevelClient is deprecated, but still can be configured like shown (make sure to read
-<<elasticsearch-migration-guide-4.4-5.0.old-client>> as well). 
-
-It should only be used to access an Elasticsearch cluster running version 7, even with the compatibility headers set 
-there are cases where the `RestHighLevelClient` cannot read the responses sent from a version 8 cluster. 
-====
-
-.RestHighLevelClient
-====
-[source,java]
-----
-import org.springframework.data.elasticsearch.client.erhlc.AbstractElasticsearchConfiguration;
-
-@Configuration
-public class RestClientConfig extends AbstractElasticsearchConfiguration {
-
-    @Override
-    @Bean
-    public RestHighLevelClient elasticsearchClient() {
-
-        final ClientConfiguration clientConfiguration = ClientConfiguration.builder()  <1>
-            .connectedTo("localhost:9200")
-            .build();
-
-        return RestClients.create(clientConfiguration).rest();                         <2>
-    }
-}
-
-// ...
-
-  @Autowired
-  RestHighLevelClient highLevelClient;
-
-  RestClient lowLevelClient = highLevelClient.lowLevelClient();                        <3>
-----
-
-<1> Use the builder to provide cluster addresses, set default `HttpHeaders` or enable SSL.
-<2> Create the RestHighLevelClient.
-<3> It is also possible to obtain the `lowLevelRest()` client.
-====
-
-[[elasticsearch.clients.reactive]]
-== Reactive Client (deprecated)
-
-The `org.springframework.data.elasticsearch.client.erhlc.ReactiveElasticsearchClient` is a non official driver based on `WebClient`.
-It uses the request/response objects provided by the Elasticsearch core project.
-Calls are directly operated on the reactive stack, **not** wrapping async (thread pool bound) responses into reactive types.
-
-[CAUTION]
-====
-This was the first reactive implementation Spring Data Elasticsearch provided, but now is deprecated in favour
-of the `org.springframework.data.elasticsearch.client.elc.ReactiveElasticsearchClient`
-which uses the functionality offered by the new Elasticsearch client libraries.
-====
-
-.Reactive REST Client (deprecated)
-====
-[source,java]
-----
-import org.springframework.data.elasticsearch.client.erhlc.AbstractReactiveElasticsearchConfiguration;
-
-@Configuration
-public class ReactiveRestClientConfig extends AbstractReactiveElasticsearchConfiguration {
-
-    @Override
-    @Bean
-    public ReactiveElasticsearchClient reactiveElasticsearchClient() {
-        final ClientConfiguration clientConfiguration = ClientConfiguration.builder() <.>
-            .connectedTo("localhost:9200") //
-            .build();
-        return ReactiveRestClients.create(clientConfiguration);
-
-    }
-}
-// ...
-
-Mono<IndexResponse> response = client.index(request ->
-
-  request.index("spring-data")
-    .id(randomID())
-    .source(singletonMap("feature", "reactive-client"));
-);
-----
-
-<.> Use the builder to provide cluster addresses, set default `HttpHeaders` or enable SSL.
-====
-
 [[elasticsearch.clients.configuration]]
 == Client Configuration
 
@@ -298,38 +206,6 @@ ClientConfiguration.builder()
 ----
 ====
 
-[[elasticsearch.clients.configuration.headers]]
-=== Elasticsearch 7 compatibility headers
-
-When using the deprecated `RestHighLevelClient` and accessing an Elasticsearch cluster that is running on version 8, it is necessary to set the compatibility headers
-https://www.elastic.co/guide/en/elasticsearch/reference/8.0/rest-api-compatibility.html[see Elasticsearch 
-documentation].
-
-For the imperative client this must be done by setting the default headers, for the reactive code this must be done using a header supplier:
-
-CAUTION: Even when these headers are set, there are cases where the response returned from the cluster cannot be 
-parsed with the client. This is not an error in Spring Data Elasticsearch.
-
-====
-[source,java]
-----
-
-HttpHeaders compatibilityHeaders = new HttpHeaders();
-compatibilityHeaders.add("Accept", "application/vnd.elasticsearch+json;compatible-with=7");
-compatibilityHeaders.add("Content-Type", "application/vnd.elasticsearch+json;"
-    + "compatible-with=7");
-
-ClientConfiguration clientConfiguration = ClientConfiguration.builder()
-    .connectedTo("localhost:9200")
-    .withProxy("localhost:8080")
-    .withBasicAuth("elastic","hcraescitsale")
-    .withDefaultHeaders(compatibilityHeaders)    // this variant for imperative code
-    .withHeaders(() -> compatibilityHeaders)     // this variant for reactive code
-    .build();
-		
-----
-====
-
 [[elasticsearch.clients.logging]]
 == Client Logging
 

src/main/asciidoc/reference/elasticsearch-migration-guide-5.1-5.2.adoc

@@ -6,6 +6,16 @@ This section describes breaking changes from version 5.1.x to 5.2.x and how remo
 [[elasticsearch-migration-guide-5.1-5.2.breaking-changes]]
 == Breaking Changes
 
-
 [[elasticsearch-migration-guide-5.1-5.2.deprecations]]
 == Deprecations
+
+=== Removal of deprecated code
+
+* All the code using the old deprecated `RestHighLevelClient` has been removed.
+The default Elasticsearch client used since version 5.0 is the (not so) new Elasticsearch Java client.
+* The `org.springframework.data.elasticsearch.client.ClientLogger` class has been removed.
+This logger was configured with the `org.springframework.data.elasticsearch.client.WIRE` setting, but was not working with all clients.
+From version 5 on, use the trace logger available in the Elasticsearch Java client, see <<elasticsearch.clients.logging>>.
+* The method `org.springframework.data.elasticsearch.core.ElasticsearchOperations.stringIdRepresentation(Object)` has been removed, use the `convertId(Object)` method defined in the same interface instead.
+* The class `org.springframework.data.elasticsearch.core.Range` has been removed, use `org.springframework.data.domain.Range` instead.
+* The methods `org.springframework.data.elasticsearch.core.query.IndexQuery.getParentId() and `setParentId(String)` have been removed, they werent used anymore and were no-ops. It has been removed from the `org.springframework.data.elasticsearch.core.query.IndexQuery` class as well.

src/main/java/org/springframework/data/elasticsearch/client/ClientConfigurationBuilder.java

@@ -59,7 +59,6 @@ class ClientConfigurationBuilder
 	@Nullable private String pathPrefix;
 	@Nullable private String proxy;
 	private Supplier<HttpHeaders> headersSupplier = HttpHeaders::new;
-	@Deprecated private final HttpClientConfigCallback httpClientConfigurer = httpClientBuilder -> httpClientBuilder;
 	private final List<ClientConfiguration.ClientConfigurationCallback<?>> clientConfigurers = new ArrayList<>();
 
 	/*
@@ -242,7 +241,7 @@ public ClientConfiguration build() {
 		}
 
 		return new DefaultClientConfiguration(hosts, headers, useSsl, sslContext, caFingerprint, soTimeout, connectTimeout,
-				pathPrefix, hostnameVerifier, proxy, httpClientConfigurer, clientConfigurers, headersSupplier);
+				pathPrefix, hostnameVerifier, proxy, clientConfigurers, headersSupplier);
 	}
 
 	private static InetSocketAddress parse(String hostAndPort) {