Polishing

Signed-off-by: Peter-Josef Meisch <pj.meisch@sothawo.com>

.mvn/jvm.config

@@ -8,3 +8,7 @@
 --add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
 --add-opens jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
 --add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED
+--add-opens=java.base/java.util=ALL-UNNAMED
+--add-opens=java.base/java.lang.reflect=ALL-UNNAMED
+--add-opens=java.base/java.text=ALL-UNNAMED
+--add-opens=java.desktop/java.awt.font=ALL-UNNAMED

.mvn/wrapper/maven-wrapper.properties

@@ -1,3 +1,3 @@
-#Thu Nov 07 09:47:28 CET 2024
+#Thu Jul 17 13:59:56 CEST 2025
 wrapperUrl=https\://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar
-distributionUrl=https\://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.9/apache-maven-3.9.9-bin.zip
+distributionUrl=https\://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.11/apache-maven-3.9.11-bin.zip

ci/pipeline.properties

@@ -1,25 +1,20 @@
 # Java versions
-java.main.tag=17.0.13_11-jdk-focal
-java.next.tag=23.0.1_11-jdk-noble
+java.main.tag=24.0.1_9-jdk-noble
+java.next.tag=24.0.1_9-jdk-noble
 
 # Docker container images - standard
 docker.java.main.image=library/eclipse-temurin:${java.main.tag}
 docker.java.next.image=library/eclipse-temurin:${java.next.tag}
 
 # Supported versions of MongoDB
-docker.mongodb.4.4.version=4.4.25
-docker.mongodb.5.0.version=5.0.21
-docker.mongodb.6.0.version=6.0.10
-docker.mongodb.7.0.version=7.0.2
-docker.mongodb.8.0.version=8.0.0
+docker.mongodb.6.0.version=6.0.23
+docker.mongodb.7.0.version=7.0.20
+docker.mongodb.8.0.version=8.0.9
 
 # Supported versions of Redis
 docker.redis.6.version=6.2.13
 docker.redis.7.version=7.2.4
 
-# Supported versions of Cassandra
-docker.cassandra.3.version=3.11.16
-
 # Docker environment settings
 docker.java.inside.basic=-v $HOME:/tmp/jenkins-home
 docker.java.inside.docker=-u root -v /var/run/docker.sock:/var/run/docker.sock -v /usr/bin/docker:/usr/bin/docker -v $HOME:/tmp/jenkins-home

pom.xml

@@ -1,16 +1,16 @@
-<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 
 	<modelVersion>4.0.0</modelVersion>
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-elasticsearch</artifactId>
-	<version>5.5.0-M2</version>
+	<version>6.0.0-SNAPSHOT</version>
 
 	<parent>
 		<groupId>org.springframework.data.build</groupId>
 		<artifactId>spring-data-parent</artifactId>
-		<version>3.5.0-M2</version>
+		<version>4.0.0-SNAPSHOT</version>
 	</parent>
 
 	<name>Spring Data Elasticsearch</name>
@@ -18,10 +18,10 @@
 	<url>https://github.com/spring-projects/spring-data-elasticsearch</url>
 
 	<properties>
-		<springdata.commons>3.5.0-M2</springdata.commons>
+		<springdata.commons>4.0.0-SNAPSHOT</springdata.commons>
 
 		<!-- version of the ElasticsearchClient	-->
-		<elasticsearch-java>8.17.2</elasticsearch-java>
+		<elasticsearch-java>9.0.3</elasticsearch-java>
 
 		<hoverfly>0.19.0</hoverfly>
 		<log4j>2.23.1</log4j>
@@ -132,6 +132,27 @@
 			</exclusions>
 		</dependency>
 
+		<!-- the old RestCLient is an optional dependency for user that still want to use it-->
+		<dependency>
+			<groupId>org.elasticsearch.client</groupId>
+			<artifactId>elasticsearch-rest-client</artifactId>
+			<version>${elasticsearch-java}</version>
+			<exclusions>
+				<exclusion>
+					<groupId>commons-logging</groupId>
+					<artifactId>commons-logging</artifactId>
+				</exclusion>
+			</exclusions>
+			<optional>true</optional>
+		</dependency>
+
+		<dependency>
+			<groupId>com.querydsl</groupId>
+			<artifactId>querydsl-core</artifactId>
+			<version>${querydsl}</version>
+			<optional>true</optional>
+		</dependency>
+
 		<!-- Jackson JSON Mapper -->
 		<dependency>
 			<groupId>com.fasterxml.jackson.core</groupId>
@@ -450,6 +471,16 @@
 	</profiles>
 
 	<repositories>
+		<repository>
+			<id>spring-snapshot</id>
+			<url>https://repo.spring.io/snapshot</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+			<releases>
+				<enabled>false</enabled>
+			</releases>
+		</repository>
 		<repository>
 			<id>spring-milestone</id>
 			<url>https://repo.spring.io/milestone</url>

src/main/antora/modules/ROOT/nav.adoc

@@ -12,6 +12,7 @@
 *** xref:migration-guides/migration-guide-5.2-5.3.adoc[]
 *** xref:migration-guides/migration-guide-5.3-5.4.adoc[]
 *** xref:migration-guides/migration-guide-5.4-5.5.adoc[]
+*** xref:migration-guides/migration-guide-5.5-6.0.adoc[]
 
 
 * xref:elasticsearch.adoc[]

src/main/antora/modules/ROOT/pages/elasticsearch/auditing.adoc

@@ -10,7 +10,7 @@ In order for the auditing code to be able to decide whether an entity instance i
 ----
 package org.springframework.data.domain;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 public interface Persistable<ID> {
     @Nullable
@@ -81,5 +81,5 @@ class MyConfiguration {
 }
 ----
 
-If your code contains more than one `AuditorAware` bean for different types, you must provide the name of the bean to use as an argument to the `auditorAwareRef` parameter of the 
- `@EnableElasticsearchAuditing` annotation. 
+If your code contains more than one `AuditorAware` bean for different types, you must provide the name of the bean to use as an argument to the `auditorAwareRef` parameter of the
+ `@EnableElasticsearchAuditing` annotation.

src/main/antora/modules/ROOT/pages/elasticsearch/clients.adoc

@@ -6,10 +6,10 @@ This chapter illustrates configuration and usage of supported Elasticsearch clie
 Spring Data Elasticsearch operates upon an Elasticsearch client (provided by Elasticsearch client libraries) that is connected to a single Elasticsearch node or a cluster.
 Although the Elasticsearch Client can be used directly to work with the cluster, applications using Spring Data Elasticsearch normally use the higher level abstractions of xref:elasticsearch/template.adoc[Elasticsearch Operations] and xref:elasticsearch/repositories/elasticsearch-repositories.adoc[Elasticsearch Repositories].
 
-[[elasticsearch.clients.restclient]]
-== Imperative Rest Client
+[[elasticsearch.clients.rest5client]]
+== Imperative Rest5Client
 
-To use the imperative (non-reactive) client, a configuration bean must be configured like this:
+To use the imperative (non-reactive) Rest5Client, a configuration bean must be configured like this:
 
 ====
 [source,java]
@@ -31,7 +31,7 @@ public class MyClientConfig extends ElasticsearchConfiguration {
 <.> for a detailed description of the builder methods see xref:elasticsearch/clients.adoc#elasticsearch.clients.configuration[Client Configuration]
 ====
 
-The javadoc:org.springframework.data.elasticsearch.client.elc.ElasticsearchConfiguration[]] class allows further configuration by overriding for example the `jsonpMapper()` or `transportOptions()` methods.
+The javadoc:org.springframework.data.elasticsearch.client.elc.ElasticsearchConfiguration[] class allows further configuration by overriding for example the `jsonpMapper()` or `transportOptions()` methods.
 
 
 The following beans can then be injected in other Spring components:
@@ -46,7 +46,81 @@ ElasticsearchOperations operations;      <.>
 ElasticsearchClient elasticsearchClient; <.>
 
 @Autowired
-RestClient restClient;                   <.>
+Rest5Client rest5Client;                 <.>
+
+@Autowired
+JsonpMapper jsonpMapper;                 <.>
+----
+
+<.> an implementation of javadoc:org.springframework.data.elasticsearch.core.ElasticsearchOperations[]
+<.> the `co.elastic.clients.elasticsearch.ElasticsearchClient` that is used.
+<.> the low level `Rest5Client` from the Elasticsearch libraries
+<.> the `JsonpMapper` user by the Elasticsearch `Transport`
+====
+
+Basically one should just use the javadoc:org.springframework.data.elasticsearch.core.ElasticsearchOperations[] to interact with the Elasticsearch cluster.
+When using repositories, this instance is used under the hood as well.
+
+[[elasticsearch.clients.restclient]]
+== Deprecated Imperative RestClient
+
+To use the imperative (non-reactive) RestClient - deprecated since version 6 - , the following dependency needs to be added, adapt the correct version. The exclusion is needed in a Spring Boot application:
+====
+[source,xml]
+----
+        <dependency>
+            <groupId>org.elasticsearch.client</groupId>
+            <artifactId>elasticsearch-rest-client</artifactId>
+            <version>${elasticsearch-client.version}</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>commons-logging</groupId>
+                    <artifactId>commons-logging</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+
+----
+====
+
+The configuration bean must be configured like this:
+
+====
+[source,java]
+----
+import org.springframework.data.elasticsearch.client.elc.ElasticsearchLegacyRestClientConfiguration;
+
+@Configuration
+public class MyClientConfig extends ElasticsearchLegacyRestClientConfiguration {
+
+	@Override
+	public ClientConfiguration clientConfiguration() {
+		return ClientConfiguration.builder()           <.>
+			.connectedTo("localhost:9200")
+			.build();
+	}
+}
+----
+
+<.> for a detailed description of the builder methods see xref:elasticsearch/clients.adoc#elasticsearch.clients.configuration[Client Configuration]
+====
+
+The javadoc:org.springframework.data.elasticsearch.client.elc.ElasticsearchConfiguration[] class allows further configuration by overriding for example the `jsonpMapper()` or `transportOptions()` methods.
+
+
+The following beans can then be injected in other Spring components:
+
+====
+[source,java]
+----
+import org.springframework.beans.factory.annotation.Autowired;@Autowired
+ElasticsearchOperations operations;      <.>
+
+@Autowired
+ElasticsearchClient elasticsearchClient; <.>
+
+@Autowired
+RestClient restClient;                 <.>
 
 @Autowired
 JsonpMapper jsonpMapper;                 <.>
@@ -61,8 +135,8 @@ JsonpMapper jsonpMapper;                 <.>
 Basically one should just use the javadoc:org.springframework.data.elasticsearch.core.ElasticsearchOperations[] to interact with the Elasticsearch cluster.
 When using repositories, this instance is used under the hood as well.
 
-[[elasticsearch.clients.reactiverestclient]]
-== Reactive Rest Client
+[[elasticsearch.clients.reactiverest5client]]
+== Reactive Rest5Client
 
 When working with the reactive stack, the configuration must be derived from a different class:
 
@@ -99,6 +173,65 @@ ReactiveElasticsearchOperations operations;      <.>
 @Autowired
 ReactiveElasticsearchClient elasticsearchClient; <.>
 
+@Autowired
+Rest5Client rest5Client;                           <.>
+
+@Autowired
+JsonpMapper jsonpMapper;                         <.>
+----
+
+the following can be injected:
+
+<.> an implementation of javadoc:org.springframework.data.elasticsearch.core.ReactiveElasticsearchOperations[]
+<.> the `org.springframework.data.elasticsearch.client.elc.ReactiveElasticsearchClient` that is used.
+This is a reactive implementation based on the Elasticsearch client implementation.
+<.> the low level `RestClient` from the Elasticsearch libraries
+<.> the `JsonpMapper` user by the Elasticsearch `Transport`
+====
+
+Basically one should just use the javadoc:org.springframework.data.elasticsearch.core.ReactiveElasticsearchOperations[] to interact with the Elasticsearch cluster.
+When using repositories, this instance is used under the hood as well.
+
+[[elasticsearch.clients.reactiverestclient]]
+== Deprecated Reactive RestClient
+
+See the section above for the imperative code to use the deprecated RestClient for the necessary dependencies to include.
+
+When working with the reactive stack, the configuration must be derived from a different class:
+
+====
+[source,java]
+----
+import org.springframework.data.elasticsearch.client.elc.ReactiveElasticsearchLegacyRestClientConfiguration;
+
+@Configuration
+public class MyClientConfig extends ReactiveElasticsearchLegacyRestClientConfiguration {
+
+	@Override
+	public ClientConfiguration clientConfiguration() {
+		return ClientConfiguration.builder()           <.>
+			.connectedTo("localhost:9200")
+			.build();
+	}
+}
+----
+
+<.> for a detailed description of the builder methods see xref:elasticsearch/clients.adoc#elasticsearch.clients.configuration[Client Configuration]
+====
+
+The javadoc:org.springframework.data.elasticsearch.client.elc.ReactiveElasticsearchConfiguration[] class allows further configuration by overriding for example the `jsonpMapper()` or `transportOptions()` methods.
+
+The following beans can then be injected in other Spring components:
+
+====
+[source,java]
+----
+@Autowired
+ReactiveElasticsearchOperations operations;      <.>
+
+@Autowired
+ReactiveElasticsearchClient elasticsearchClient; <.>
+
 @Autowired
 RestClient restClient;                           <.>
 
@@ -183,8 +316,8 @@ In the case this is not enough, the user can add callback functions by using the
 
 The following callbacks are provided:
 
-[[elasticsearch.clients.configuration.callbacks.rest]]
-==== Configuration of the low level Elasticsearch `RestClient`:
+[[elasticsearch.clients.configuration.callbacks.rest5]]
+==== Configuration of the low level Elasticsearch `Rest5Client`:
 
 This callback provides a `org.elasticsearch.client.RestClientBuilder` that can be used to configure the Elasticsearch
 `RestClient`:
@@ -193,7 +326,24 @@ This callback provides a `org.elasticsearch.client.RestClientBuilder` that can b
 ----
 ClientConfiguration.builder()
     .connectedTo("localhost:9200", "localhost:9291")
-    .withClientConfigurer(ElasticsearchClients.ElasticsearchRestClientConfigurationCallback.from(restClientBuilder -> {
+    .withClientConfigurer(Rest5Clients.ElasticsearchRest5ClientConfigurationCallback.from(restClientBuilder -> {
+        // configure the Elasticsearch Rest5Client
+        return restClientBuilder;
+    }))
+    .build();
+----
+====
+[[elasticsearch.clients.configuration.callbacks.rest]]
+==== Configuration of the deprecated low level Elasticsearch `RestClient`:
+
+This callback provides a `org.elasticsearch.client.RestClientBuilder` that can be used to configure the Elasticsearch
+`RestClient`:
+====
+[source,java]
+----
+ClientConfiguration.builder()
+    .connectedTo("localhost:9200", "localhost:9291")
+    .withClientConfigurer(RestClients.ElasticsearchRestClientConfigurationCallback.from(restClientBuilder -> {
         // configure the Elasticsearch RestClient
         return restClientBuilder;
     }))
@@ -201,10 +351,29 @@ ClientConfiguration.builder()
 ----
 ====
 
-[[elasticsearch.clients.configurationcallbacks.httpasync]]
-==== Configuration of the HttpAsyncClient used by the low level Elasticsearch `RestClient`:
+[[elasticsearch.clients.configurationcallbacks.httpasync5]]
+==== Configuration of the HttpAsyncClient used by the low level Elasticsearch `Rest5Client`:
 
-This callback provides a `org.apache.http.impl.nio.client.HttpAsyncClientBuilder` to configure the HttpCLient that is
+This callback provides a `org.apache.hc.client5.http.impl.async.HttpAsyncClientBuilder` to configure the HttpClient that is
+used by the `Rest5Client`.
+
+====
+[source,java]
+----
+ClientConfiguration.builder()
+    .connectedTo("localhost:9200", "localhost:9291")
+    .withClientConfigurer(Rest5Clients.ElasticsearchHttpClientConfigurationCallback.from(httpAsyncClientBuilder -> {
+        // configure the HttpAsyncClient
+        return httpAsyncClientBuilder;
+    }))
+    .build();
+----
+====
+
+[[elasticsearch.clients.configurationcallbacks.httpasync]]
+==== Configuration of the HttpAsyncClient used by the deprecated low level Elasticsearch `RestClient`:
+
+This callback provides a `org.apache.http.impl.nio.client.HttpAsyncClientBuilder` to configure the HttpClient that is
 used by the `RestClient`.
 
 ====
@@ -212,7 +381,7 @@ used by the `RestClient`.
 ----
 ClientConfiguration.builder()
     .connectedTo("localhost:9200", "localhost:9291")
-    .withClientConfigurer(ElasticsearchClients.ElasticsearchHttpClientConfigurationCallback.from(httpAsyncClientBuilder -> {
+    .withClientConfigurer(RestClients.ElasticsearchHttpClientConfigurationCallback.from(httpAsyncClientBuilder -> {
         // configure the HttpAsyncClient
         return httpAsyncClientBuilder;
     }))

src/main/antora/modules/ROOT/pages/elasticsearch/elasticsearch-new.adoc

@@ -1,11 +1,21 @@
 [[new-features]]
 = What's new
 
+[[new-features.6-0-0]]
+== New in Spring Data Elasticsearch 6.0
+
+* Upgarde to Spring 7
+* Switch to jspecify nullability annotations
+* Upgrade to Elasticsearch 9.0.3
+* Use the new Elasticsearch Rest5Client as default
+
+
 [[new-features.5-5-0]]
 == New in Spring Data Elasticsearch 5.5
 
-* Upgrade to Elasticsearch 8.17.2.
+* Upgrade to Elasticsearch 8.18.1.
 * Add support for the `@SearchTemplateQuery` annotation on repository methods.
+* Scripted field properties of type collection can be populated from scripts returning arrays.
 
 [[new-features.5-4-0]]
 == New in Spring Data Elasticsearch 5.4

src/main/antora/modules/ROOT/pages/elasticsearch/scripted-and-runtime-fields.adoc

@@ -20,12 +20,12 @@ Whereas the birthdate is fix, the age depends on the time when a query is issued
 ====
 [source,java]
 ----
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.annotation.Id;
 import org.springframework.data.elasticsearch.annotations.DateFormat;
 import org.springframework.data.elasticsearch.annotations.Document;
 import org.springframework.data.elasticsearch.annotations.Field;
 import org.springframework.data.elasticsearch.annotations.ScriptedField;
-import org.springframework.lang.Nullable;
 
 import java.time.LocalDate;
 import java.time.format.DateTimeFormatter;

src/main/antora/modules/ROOT/pages/elasticsearch/versions.adoc

@@ -6,10 +6,11 @@ The following table shows the Elasticsearch and Spring versions that are used by
 [cols="^,^,^,^",options="header"]
 |===
 | Spring Data Release Train | Spring Data Elasticsearch | Elasticsearch | Spring Framework
-| 2025.0 (in development) | 5.5.x | 8.17.2 | 6.2.x
+| 2025.1 (in development) | 6.0.x | 9.0.3 | 7.0.x
+| 2025.0 | 5.5.x | 8.18.1 | 6.2.x
 | 2024.1 | 5.4.x | 8.15.5 | 6.1.x
-| 2024.0 | 5.3.x | 8.13.4 | 6.1.x
-| 2023.1 (Vaughan) | 5.2.xfootnote:oom[Out of maintenance] | 8.11.1 | 6.1.x
+| 2024.0 | 5.3.xfootnote:oom[Out of maintenance] | 8.13.4 | 6.1.x
+| 2023.1 (Vaughan) | 5.2.xfootnote:oom[] | 8.11.1 | 6.1.x
 | 2023.0 (Ullmann) | 5.1.xfootnote:oom[] | 8.7.1 | 6.0.x
 | 2022.0 (Turing) | 5.0.xfootnote:oom[] | 8.5.3 | 6.0.x
 | 2021.2 (Raj) | 4.4.xfootnote:oom[] | 7.17.3 | 5.3.x

src/main/antora/modules/ROOT/pages/migration-guides/migration-guide-5.5-6.0.adoc

@@ -0,0 +1,27 @@
+[[elasticsearch-migration-guide-5.5-6.0]]
+= Upgrading from 5.5.x to 6.0.x
+
+This section describes breaking changes from version 5.5.x to 6.0.x and how removed features can be replaced by new introduced features.
+
+[[elasticsearch-migration-guide-5.5-6.0.breaking-changes]]
+== Breaking Changes
+
+From version 6.0 on, Spring Data Elasticsearch uses the Elasticsearch 9 libraries and as default the new `Rest5Client` provided by these libraries. It is still possible to use the old `RestClient`, check xref:elasticsearch/clients.adoc[Elasticsearch clients] for information. The configuration callbacks for this `RestClient` have been moved from `org.springframework.data.elasticsearch.client.elc.ElasticsearchClients` to the `org.springframework.data.elasticsearch.client.elc.rest_client.RestClients` class.
+
+In the `org.springframework.data.elasticsearch.core.query.UpdateQuery` class the type of the two fields `ifSeqNo` and `ifPrimaryTerm` has changed from `Integer` to `Long` to align with the normal query and the underlying Elasticsearch client.
+
+[[elasticsearch-migration-guide-5.5-6.0.deprecations]]
+== Deprecations
+
+All the code using the old `RestClient` has been moved to the `org.springframework.data.elasticsearch.client.elc.rest_client` package and has been deprecated. Users should switch to the classes from the `org.springframework.data.elasticsearch.client.elc.rest5_client` package.
+
+
+=== Removals
+
+The `org.springframework.data.elasticsearch.core.query.ScriptType` enum has been removed. To distinguish between an inline and a stored script set the appropriate values in the `org.springframework.data.elasticsearch.core.query.ScriptData` record.
+
+These methods have been removed because the Elasticsearch Client 9 does not support them anymore:
+```
+org.springframework.data.elasticsearch.client.elc.ReactiveElasticsearchIndicesClient.unfreeze(UnfreezeRequest)
+org.springframework.data.elasticsearch.client.elc.ReactiveElasticsearchIndicesClient.unfreeze(Function<UnfreezeRequest.Builder, ObjectBuilder<UnfreezeRequest>>)
+```

src/main/java/org/springframework/data/elasticsearch/ElasticsearchErrorCause.java

@@ -15,10 +15,10 @@
  */
 package org.springframework.data.elasticsearch;
 
-import org.springframework.lang.Nullable;
-
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Object describing an Elasticsearch error
  *
@@ -26,8 +26,7 @@ import java.util.List;
  * @since 4.4
  */
 public class ElasticsearchErrorCause {
-	@Nullable
-	private final String type;
+	@Nullable private final String type;
 
 	private final String reason;
 

src/main/java/org/springframework/data/elasticsearch/UncategorizedElasticsearchException.java

@@ -15,8 +15,8 @@
  */
 package org.springframework.data.elasticsearch;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.dao.UncategorizedDataAccessException;
-import org.springframework.lang.Nullable;
 
 /**
  * @author Peter-Josef Meisch

src/main/java/org/springframework/data/elasticsearch/annotations/package-info.java

@@ -1,3 +1,2 @@
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.annotations;

src/main/java/org/springframework/data/elasticsearch/aot/SpringDataElasticsearchRuntimeHints.java

@@ -19,6 +19,7 @@ import static org.springframework.data.elasticsearch.aot.ElasticsearchAotPredica
 
 import java.util.Arrays;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.aot.hint.MemberCategory;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
@@ -32,7 +33,6 @@ import org.springframework.data.elasticsearch.core.event.ReactiveAfterConvertCal
 import org.springframework.data.elasticsearch.core.event.ReactiveAfterLoadCallback;
 import org.springframework.data.elasticsearch.core.event.ReactiveAfterSaveCallback;
 import org.springframework.data.elasticsearch.core.event.ReactiveBeforeConvertCallback;
-import org.springframework.lang.Nullable;
 
 /**
  * @author Peter-Josef Meisch

src/main/java/org/springframework/data/elasticsearch/aot/package-info.java

@@ -1,3 +1,2 @@
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.aot;

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

@@ -25,8 +25,8 @@ import java.util.function.Supplier;
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLContext;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.support.HttpHeaders;
-import org.springframework.lang.Nullable;
 
 /**
  * Configuration interface exposing common client configuration properties for Elasticsearch clients.
@@ -127,10 +127,16 @@ public interface ClientConfiguration {
 	Optional<String> getCaFingerprint();
 
 	/**
-	 * Returns the {@link HostnameVerifier} to use. Can be {@link Optional#empty()} if not configured.
+	 * Returns the {@link HostnameVerifier} to use. Must be {@link Optional#empty()} if not configured.
+	 * Cannot be used with the Rest5Client used from Elasticsearch 9 on as the underlying Apache http components 5 does not offer a way
+	 * to set this. Users that need a hostname verifier must integrate this in a SSLContext.
+	 * Returning a value here is ignored in this case
 	 *
 	 * @return the {@link HostnameVerifier} to use. Can be {@link Optional#empty()} if not configured.
+	 * @deprecated since 6.0
 	 */
+	// todo #3117 document this
+	@Deprecated(since = "6.0", forRemoval=true)
 	Optional<HostnameVerifier> getHostNameVerifier();
 
 	/**

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

@@ -25,11 +25,11 @@ import java.util.function.Supplier;
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLContext;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.client.ClientConfiguration.ClientConfigurationBuilderWithRequiredEndpoint;
 import org.springframework.data.elasticsearch.client.ClientConfiguration.MaybeSecureClientConfigurationBuilder;
 import org.springframework.data.elasticsearch.client.ClientConfiguration.TerminalClientConfigurationBuilder;
 import org.springframework.data.elasticsearch.support.HttpHeaders;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

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

@@ -24,9 +24,8 @@ import java.util.function.Supplier;
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLContext;
 
-import org.elasticsearch.client.RestClientBuilder.HttpClientConfigCallback;
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.support.HttpHeaders;
-import org.springframework.lang.Nullable;
 
 /**
  * Default {@link ClientConfiguration} implementation.

src/main/java/org/springframework/data/elasticsearch/client/elc/AbstractQueryProcessor.java

@@ -17,10 +17,10 @@ package org.springframework.data.elasticsearch.client.elc;
 
 import java.util.function.Consumer;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.query.CriteriaQuery;
 import org.springframework.data.elasticsearch.core.query.Query;
 import org.springframework.data.elasticsearch.core.query.StringQuery;
-import org.springframework.lang.Nullable;
 
 /**
  * An abstract class that serves as a base for query processors. It provides a common interface and basic functionality
@@ -38,8 +38,8 @@ public abstract class AbstractQueryProcessor {
 	 * @param queryConverter correct mapped field names and the values to the converted values.
 	 * @return an Elasticsearch {@literal query}.
 	 */
-	@Nullable
-	static co.elastic.clients.elasticsearch._types.query_dsl.Query getEsQuery(@Nullable Query query,
+
+	static co.elastic.clients.elasticsearch._types.query_dsl.@Nullable Query getEsQuery(@Nullable Query query,
 			@Nullable Consumer<Query> queryConverter) {
 		if (query == null) {
 			return null;

src/main/java/org/springframework/data/elasticsearch/client/elc/CriteriaQueryProcessor.java

@@ -31,13 +31,13 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Objects;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.annotations.FieldType;
 import org.springframework.data.elasticsearch.core.query.Criteria;
 import org.springframework.data.elasticsearch.core.query.Field;
 import org.springframework.data.elasticsearch.core.query.HasChildQuery;
 import org.springframework.data.elasticsearch.core.query.HasParentQuery;
 import org.springframework.data.elasticsearch.core.query.InnerHitsQuery;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/client/elc/DocumentAdapters.java

@@ -24,16 +24,9 @@ import co.elastic.clients.elasticsearch.core.search.Hit;
 import co.elastic.clients.elasticsearch.core.search.NestedIdentity;
 import co.elastic.clients.json.JsonData;
 import co.elastic.clients.json.JsonpMapper;
-
-import java.util.Collections;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.function.Function;
-import java.util.stream.Collectors;
-
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.MultiGetItem;
 import org.springframework.data.elasticsearch.core.document.Document;
 import org.springframework.data.elasticsearch.core.document.Explanation;
@@ -41,9 +34,15 @@ import org.springframework.data.elasticsearch.core.document.NestedMetaData;
 import org.springframework.data.elasticsearch.core.document.SearchDocument;
 import org.springframework.data.elasticsearch.core.document.SearchDocumentAdapter;
 import org.springframework.data.elasticsearch.core.document.SearchDocumentResponse;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
 /**
  * Utility class to adapt different Elasticsearch responses to a
  * {@link org.springframework.data.elasticsearch.core.document.Document}
@@ -55,187 +54,188 @@ import org.springframework.util.Assert;
  */
 final class DocumentAdapters {
 
-	private static final Log LOGGER = LogFactory.getLog(DocumentAdapters.class);
+    private static final Log LOGGER = LogFactory.getLog(DocumentAdapters.class);
 
-	private DocumentAdapters() {}
+    private DocumentAdapters() {
+    }
 
-	/**
-	 * Creates a {@link SearchDocument} from a {@link Hit} returned by the Elasticsearch client.
-	 *
-	 * @param hit the hit object
-	 * @param jsonpMapper to map JsonData objects
-	 * @return the created {@link SearchDocument}
-	 */
-	public static SearchDocument from(Hit<?> hit, JsonpMapper jsonpMapper) {
+    /**
+     * Creates a {@link SearchDocument} from a {@link Hit} returned by the Elasticsearch client.
+     *
+     * @param hit         the hit object
+     * @param jsonpMapper to map JsonData objects
+     * @return the created {@link SearchDocument}
+     */
+    public static SearchDocument from(Hit<?> hit, JsonpMapper jsonpMapper) {
 
-		Assert.notNull(hit, "hit must not be null");
+        Assert.notNull(hit, "hit must not be null");
 
-		Map<String, List<String>> highlightFields = hit.highlight();
+        Map<String, List<String>> highlightFields = hit.highlight();
 
-		Map<String, SearchDocumentResponse> innerHits = new LinkedHashMap<>();
-		hit.innerHits().forEach((name, innerHitsResult) -> {
-			// noinspection ReturnOfNull
-			innerHits.put(name, SearchDocumentResponseBuilder.from(innerHitsResult.hits(), null, null, null, 0, null, null,
-					searchDocument -> null, jsonpMapper));
-		});
+        Map<String, SearchDocumentResponse> innerHits = new LinkedHashMap<>();
+        hit.innerHits().forEach((name, innerHitsResult) -> {
+            // noinspection ReturnOfNull
+            innerHits.put(name, SearchDocumentResponseBuilder.from(innerHitsResult.hits(), null, null, null, 0, null, null,
+                    searchDocument -> null, jsonpMapper));
+        });
 
-		NestedMetaData nestedMetaData = from(hit.nested());
+        NestedMetaData nestedMetaData = from(hit.nested());
 
-		Explanation explanation = from(hit.explanation());
+        Explanation explanation = from(hit.explanation());
 
-		List<String> matchedQueries = hit.matchedQueries();
+        Map<String, Double> matchedQueries = hit.matchedQueries();
 
-		Function<Map<String, JsonData>, EntityAsMap> fromFields = fields -> {
-			StringBuilder sb = new StringBuilder("{");
-			final boolean[] firstField = { true };
-			hit.fields().forEach((key, jsonData) -> {
-				if (!firstField[0]) {
-					sb.append(',');
-				}
-				sb.append('"').append(key).append("\":") //
-						.append(jsonData.toJson(jsonpMapper).toString());
-				firstField[0] = false;
-			});
-			sb.append('}');
-			return new EntityAsMap().fromJson(sb.toString());
-		};
+        Function<Map<String, JsonData>, EntityAsMap> fromFields = fields -> {
+            StringBuilder sb = new StringBuilder("{");
+            final boolean[] firstField = {true};
+            hit.fields().forEach((key, jsonData) -> {
+                if (!firstField[0]) {
+                    sb.append(',');
+                }
+                sb.append('"').append(key).append("\":") //
+                        .append(jsonData.toJson(jsonpMapper).toString());
+                firstField[0] = false;
+            });
+            sb.append('}');
+            return new EntityAsMap().fromJson(sb.toString());
+        };
 
-		EntityAsMap hitFieldsAsMap = fromFields.apply(hit.fields());
+        EntityAsMap hitFieldsAsMap = fromFields.apply(hit.fields());
 
-		Map<String, List<Object>> documentFields = new LinkedHashMap<>();
-		hitFieldsAsMap.forEach((key, value) -> {
-			if (value instanceof List) {
-				// noinspection unchecked
-				documentFields.put(key, (List<Object>) value);
-			} else {
-				documentFields.put(key, Collections.singletonList(value));
-			}
-		});
+        Map<String, List<Object>> documentFields = new LinkedHashMap<>();
+        hitFieldsAsMap.forEach((key, value) -> {
+            if (value instanceof List) {
+                // noinspection unchecked
+                documentFields.put(key, (List<Object>) value);
+            } else {
+                documentFields.put(key, Collections.singletonList(value));
+            }
+        });
 
-		Document document;
-		Object source = hit.source();
-		if (source == null) {
-			document = Document.from(hitFieldsAsMap);
-		} else {
-			if (source instanceof EntityAsMap entityAsMap) {
-				document = Document.from(entityAsMap);
-			} else if (source instanceof JsonData jsonData) {
-				document = Document.from(jsonData.to(EntityAsMap.class));
-			} else {
+        Document document;
+        Object source = hit.source();
+        if (source == null) {
+            document = Document.from(hitFieldsAsMap);
+        } else {
+            if (source instanceof EntityAsMap entityAsMap) {
+                document = Document.from(entityAsMap);
+            } else if (source instanceof JsonData jsonData) {
+                document = Document.from(jsonData.to(EntityAsMap.class));
+            } else {
 
-				if (LOGGER.isWarnEnabled()) {
-					LOGGER.warn(String.format("Cannot map from type " + source.getClass().getName()));
-				}
-				document = Document.create();
-			}
-		}
-		document.setIndex(hit.index());
-		document.setId(hit.id());
+                if (LOGGER.isWarnEnabled()) {
+                    LOGGER.warn(String.format("Cannot map from type " + source.getClass().getName()));
+                }
+                document = Document.create();
+            }
+        }
+        document.setIndex(hit.index());
+        document.setId(hit.id());
 
-		if (hit.version() != null) {
-			document.setVersion(hit.version());
-		}
-		document.setSeqNo(hit.seqNo() != null && hit.seqNo() >= 0 ? hit.seqNo() : -2); // -2 was the default value in the
-		// old client
-		document.setPrimaryTerm(hit.primaryTerm() != null && hit.primaryTerm() > 0 ? hit.primaryTerm() : 0);
+        if (hit.version() != null) {
+            document.setVersion(hit.version());
+        }
+        document.setSeqNo(hit.seqNo() != null && hit.seqNo() >= 0 ? hit.seqNo() : -2); // -2 was the default value in the
+        // old client
+        document.setPrimaryTerm(hit.primaryTerm() != null && hit.primaryTerm() > 0 ? hit.primaryTerm() : 0);
 
-		float score = hit.score() != null ? hit.score().floatValue() : Float.NaN;
-		return new SearchDocumentAdapter(document, score, hit.sort().stream().map(TypeUtils::toObject).toArray(),
-				documentFields, highlightFields, innerHits, nestedMetaData, explanation, matchedQueries, hit.routing());
-	}
+        float score = hit.score() != null ? hit.score().floatValue() : Float.NaN;
+        return new SearchDocumentAdapter(document, score, hit.sort().stream().map(TypeUtils::toObject).toArray(),
+                documentFields, highlightFields, innerHits, nestedMetaData, explanation, matchedQueries, hit.routing());
+    }
 
-	public static SearchDocument from(CompletionSuggestOption<EntityAsMap> completionSuggestOption) {
+    public static SearchDocument from(CompletionSuggestOption<EntityAsMap> completionSuggestOption) {
 
-		Document document = completionSuggestOption.source() != null ? Document.from(completionSuggestOption.source())
-				: Document.create();
-		document.setIndex(completionSuggestOption.index());
+        Document document = completionSuggestOption.source() != null ? Document.from(completionSuggestOption.source())
+                : Document.create();
+        document.setIndex(completionSuggestOption.index());
 
-		if (completionSuggestOption.id() != null) {
-			document.setId(completionSuggestOption.id());
-		}
+        if (completionSuggestOption.id() != null) {
+            document.setId(completionSuggestOption.id());
+        }
 
-		float score = completionSuggestOption.score() != null ? completionSuggestOption.score().floatValue() : Float.NaN;
-		return new SearchDocumentAdapter(document, score, new Object[] {}, Collections.emptyMap(), Collections.emptyMap(),
-				Collections.emptyMap(), null, null, null, completionSuggestOption.routing());
-	}
+        float score = completionSuggestOption.score() != null ? completionSuggestOption.score().floatValue() : Float.NaN;
+        return new SearchDocumentAdapter(document, score, new Object[]{}, Collections.emptyMap(), Collections.emptyMap(),
+                Collections.emptyMap(), null, null, null, completionSuggestOption.routing());
+    }
 
-	@Nullable
-	private static Explanation from(@Nullable co.elastic.clients.elasticsearch.core.explain.Explanation explanation) {
+    @Nullable
+    private static Explanation from(co.elastic.clients.elasticsearch.core.explain.@Nullable Explanation explanation) {
 
-		if (explanation == null) {
-			return null;
-		}
-		List<Explanation> details = explanation.details().stream().map(DocumentAdapters::from).collect(Collectors.toList());
-		return new Explanation(true, (double) explanation.value(), explanation.description(), details);
-	}
+        if (explanation == null) {
+            return null;
+        }
+        List<Explanation> details = explanation.details().stream().map(DocumentAdapters::from).collect(Collectors.toList());
+        return new Explanation(true, (double) explanation.value(), explanation.description(), details);
+    }
 
-	private static Explanation from(ExplanationDetail explanationDetail) {
+    private static Explanation from(ExplanationDetail explanationDetail) {
 
-		List<Explanation> details = explanationDetail.details().stream().map(DocumentAdapters::from)
-				.collect(Collectors.toList());
-		return new Explanation(null, (double) explanationDetail.value(), explanationDetail.description(), details);
-	}
+        List<Explanation> details = explanationDetail.details().stream().map(DocumentAdapters::from)
+                .collect(Collectors.toList());
+        return new Explanation(null, (double) explanationDetail.value(), explanationDetail.description(), details);
+    }
 
-	@Nullable
-	private static NestedMetaData from(@Nullable NestedIdentity nestedIdentity) {
+    @Nullable
+    private static NestedMetaData from(@Nullable NestedIdentity nestedIdentity) {
 
-		if (nestedIdentity == null) {
-			return null;
-		}
+        if (nestedIdentity == null) {
+            return null;
+        }
 
-		NestedMetaData child = from(nestedIdentity.nested());
-		return NestedMetaData.of(nestedIdentity.field(), nestedIdentity.offset(), child);
-	}
+        NestedMetaData child = from(nestedIdentity.nested());
+        return NestedMetaData.of(nestedIdentity.field(), nestedIdentity.offset(), child);
+    }
 
-	/**
-	 * Creates a {@link Document} from a {@link GetResponse} where the found document is contained as {@link EntityAsMap}.
-	 *
-	 * @param getResponse the response instance
-	 * @return the Document
-	 */
-	@Nullable
-	public static Document from(GetResult<EntityAsMap> getResponse) {
+    /**
+     * Creates a {@link Document} from a {@link GetResponse} where the found document is contained as {@link EntityAsMap}.
+     *
+     * @param getResponse the response instance
+     * @return the Document
+     */
+    @Nullable
+    public static Document from(GetResult<EntityAsMap> getResponse) {
 
-		Assert.notNull(getResponse, "getResponse must not be null");
+        Assert.notNull(getResponse, "getResponse must not be null");
 
-		if (!getResponse.found()) {
-			return null;
-		}
+        if (!getResponse.found()) {
+            return null;
+        }
 
-		Document document = getResponse.source() != null ? Document.from(getResponse.source()) : Document.create();
-		document.setIndex(getResponse.index());
-		document.setId(getResponse.id());
+        Document document = getResponse.source() != null ? Document.from(getResponse.source()) : Document.create();
+        document.setIndex(getResponse.index());
+        document.setId(getResponse.id());
 
-		if (getResponse.version() != null) {
-			document.setVersion(getResponse.version());
-		}
+        if (getResponse.version() != null) {
+            document.setVersion(getResponse.version());
+        }
 
-		if (getResponse.seqNo() != null) {
-			document.setSeqNo(getResponse.seqNo());
-		}
+        if (getResponse.seqNo() != null) {
+            document.setSeqNo(getResponse.seqNo());
+        }
 
-		if (getResponse.primaryTerm() != null) {
-			document.setPrimaryTerm(getResponse.primaryTerm());
-		}
+        if (getResponse.primaryTerm() != null) {
+            document.setPrimaryTerm(getResponse.primaryTerm());
+        }
 
-		return document;
-	}
+        return document;
+    }
 
-	/**
-	 * Creates a list of {@link MultiGetItem}s from a {@link MgetResponse} where the data is contained as
-	 * {@link EntityAsMap} instances.
-	 *
-	 * @param mgetResponse the response instance
-	 * @return list of multiget items
-	 */
-	public static List<MultiGetItem<Document>> from(MgetResponse<EntityAsMap> mgetResponse) {
+    /**
+     * Creates a list of {@link MultiGetItem}s from a {@link MgetResponse} where the data is contained as
+     * {@link EntityAsMap} instances.
+     *
+     * @param mgetResponse the response instance
+     * @return list of multiget items
+     */
+    public static List<MultiGetItem<Document>> from(MgetResponse<EntityAsMap> mgetResponse) {
 
-		Assert.notNull(mgetResponse, "mgetResponse must not be null");
+        Assert.notNull(mgetResponse, "mgetResponse must not be null");
 
-		return mgetResponse.docs().stream() //
-				.map(itemResponse -> MultiGetItem.of( //
-						itemResponse.isFailure() ? null : from(itemResponse.result()), //
-						ResponseConverter.getFailure(itemResponse)))
-				.collect(Collectors.toList());
-	}
+        return mgetResponse.docs().stream() //
+                .map(itemResponse -> MultiGetItem.of( //
+                        itemResponse.isFailure() ? null : from(itemResponse.result()), //
+                        ResponseConverter.getFailure(itemResponse)))
+                .collect(Collectors.toList());
+    }
 }

src/main/java/org/springframework/data/elasticsearch/client/elc/ElasticsearchAggregations.java

@@ -22,8 +22,8 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.AggregationsContainer;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/client/elc/ElasticsearchClientFactoryBean.java

@@ -19,12 +19,12 @@ import co.elastic.clients.elasticsearch.ElasticsearchClient;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.FactoryBeanNotInitializedException;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.data.elasticsearch.client.ClientConfiguration;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/client/elc/ElasticsearchClients.java

@@ -15,44 +15,38 @@
  */
 package org.springframework.data.elasticsearch.client.elc;
 
+import static org.springframework.data.elasticsearch.client.elc.rest5_client.Rest5Clients.*;
+import static org.springframework.data.elasticsearch.client.elc.rest_client.RestClients.*;
+
 import co.elastic.clients.elasticsearch.ElasticsearchClient;
 import co.elastic.clients.json.JsonpMapper;
 import co.elastic.clients.json.jackson.JacksonJsonpMapper;
 import co.elastic.clients.transport.ElasticsearchTransport;
 import co.elastic.clients.transport.TransportOptions;
-import co.elastic.clients.transport.TransportUtils;
 import co.elastic.clients.transport.Version;
+import co.elastic.clients.transport.rest5_client.Rest5ClientOptions;
+import co.elastic.clients.transport.rest5_client.Rest5ClientTransport;
+import co.elastic.clients.transport.rest5_client.low_level.RequestOptions;
+import co.elastic.clients.transport.rest5_client.low_level.Rest5Client;
 import co.elastic.clients.transport.rest_client.RestClientOptions;
 import co.elastic.clients.transport.rest_client.RestClientTransport;
 
-import java.net.InetSocketAddress;
-import java.time.Duration;
-import java.util.Arrays;
-import java.util.List;
 import java.util.function.Consumer;
 import java.util.function.Function;
-import java.util.function.Supplier;
-import java.util.stream.Collectors;
 
-import org.apache.http.HttpHost;
-import org.apache.http.HttpRequest;
-import org.apache.http.HttpRequestInterceptor;
-import org.apache.http.client.config.RequestConfig;
 import org.apache.http.entity.ContentType;
 import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
-import org.apache.http.message.BasicHeader;
 import org.apache.http.message.BasicNameValuePair;
-import org.apache.http.protocol.HttpContext;
-import org.elasticsearch.client.RequestOptions;
 import org.elasticsearch.client.RestClient;
-import org.elasticsearch.client.RestClientBuilder;
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.client.ClientConfiguration;
-import org.springframework.data.elasticsearch.support.HttpHeaders;
-import org.springframework.lang.Nullable;
+import org.springframework.data.elasticsearch.support.VersionInfo;
 import org.springframework.util.Assert;
 
 /**
- * Utility class to create the different Elasticsearch clients
+ * Utility class to create the different Elasticsearch clients. The RestClient class is the one used in Elasticsearch
+ * until version 9, it is still available, but it's use is deprecated. The Rest5Client class is the one that should be
+ * used from Elasticsearch 9 on.
  *
  * @author Peter-Josef Meisch
  * @since 4.4
@@ -119,18 +113,32 @@ public final class ElasticsearchClients {
 	 *
 	 * @param restClient the underlying {@link RestClient}
 	 * @return the {@link ReactiveElasticsearchClient}
+	 * @deprecated since 6.0, use the version with a Rest5Client.
 	 */
+	@Deprecated(since = "6.0", forRemoval = true)
 	public static ReactiveElasticsearchClient createReactive(RestClient restClient) {
 		return createReactive(restClient, null, DEFAULT_JSONP_MAPPER);
 	}
 
+	/**
+	 * Creates a new {@link ReactiveElasticsearchClient}.
+	 *
+	 * @param rest5Client the underlying {@link RestClient}
+	 * @return the {@link ReactiveElasticsearchClient}
+	 */
+	public static ReactiveElasticsearchClient createReactive(Rest5Client rest5Client) {
+		return createReactive(rest5Client, null, DEFAULT_JSONP_MAPPER);
+	}
+
 	/**
 	 * Creates a new {@link ReactiveElasticsearchClient}.
 	 *
 	 * @param restClient the underlying {@link RestClient}
 	 * @param transportOptions options to be added to each request.
 	 * @return the {@link ReactiveElasticsearchClient}
+	 * @deprecated since 6.0, use the version with a Rest5Client.
 	 */
+	@Deprecated(since = "6.0", forRemoval = true)
 	public static ReactiveElasticsearchClient createReactive(RestClient restClient,
 			@Nullable TransportOptions transportOptions, JsonpMapper jsonpMapper) {
 
@@ -139,6 +147,21 @@ public final class ElasticsearchClients {
 		var transport = getElasticsearchTransport(restClient, REACTIVE_CLIENT, transportOptions, jsonpMapper);
 		return createReactive(transport);
 	}
+	/**
+	 * Creates a new {@link ReactiveElasticsearchClient}.
+	 *
+	 * @param rest5Client the underlying {@link RestClient}
+	 * @param transportOptions options to be added to each request.
+	 * @return the {@link ReactiveElasticsearchClient}
+	 */
+	public static ReactiveElasticsearchClient createReactive(Rest5Client rest5Client,
+			@Nullable TransportOptions transportOptions, JsonpMapper jsonpMapper) {
+
+		Assert.notNull(rest5Client, "restClient must not be null");
+
+		var transport = getElasticsearchTransport(rest5Client, REACTIVE_CLIENT, transportOptions, jsonpMapper);
+		return createReactive(transport);
+	}
 
 	/**
 	 * Creates a new {@link ReactiveElasticsearchClient} that uses the given {@link ElasticsearchTransport}.
@@ -156,17 +179,21 @@ public final class ElasticsearchClients {
 
 	// region imperative client
 	/**
-	 * Creates a new imperative {@link ElasticsearchClient}
+	 * Creates a new imperative {@link ElasticsearchClient}. This uses a RestClient, if the old RestClient is needed, this
+	 * must be created with the {@link org.springframework.data.elasticsearch.client.elc.rest_client.RestClients} class
+	 * and passed in as parameter.
 	 *
 	 * @param clientConfiguration configuration options, must not be {@literal null}.
 	 * @return the {@link ElasticsearchClient}
 	 */
 	public static ElasticsearchClient createImperative(ClientConfiguration clientConfiguration) {
-		return createImperative(getRestClient(clientConfiguration), null, DEFAULT_JSONP_MAPPER);
+		return createImperative(getRest5Client(clientConfiguration), null, DEFAULT_JSONP_MAPPER);
 	}
 
 	/**
-	 * Creates a new imperative {@link ElasticsearchClient}
+	 * Creates a new imperative {@link ElasticsearchClient}. This uses a RestClient, if the old RestClient is needed, this
+	 * must be created with the {@link org.springframework.data.elasticsearch.client.elc.rest_client.RestClients} class
+	 * and passed in as parameter.
 	 *
 	 * @param clientConfiguration configuration options, must not be {@literal null}.
 	 * @param transportOptions options to be added to each request.
@@ -174,7 +201,7 @@ public final class ElasticsearchClients {
 	 */
 	public static ElasticsearchClient createImperative(ClientConfiguration clientConfiguration,
 			TransportOptions transportOptions) {
-		return createImperative(getRestClient(clientConfiguration), transportOptions, DEFAULT_JSONP_MAPPER);
+		return createImperative(getRest5Client(clientConfiguration), transportOptions, DEFAULT_JSONP_MAPPER);
 	}
 
 	/**
@@ -182,11 +209,23 @@ public final class ElasticsearchClients {
 	 *
 	 * @param restClient the RestClient to use
 	 * @return the {@link ElasticsearchClient}
+	 * @deprecated since 6.0, use the version with a Rest5Client.
 	 */
+	@Deprecated(since = "6.0", forRemoval = true)
 	public static ElasticsearchClient createImperative(RestClient restClient) {
 		return createImperative(restClient, null, DEFAULT_JSONP_MAPPER);
 	}
 
+	/**
+	 * Creates a new imperative {@link ElasticsearchClient}
+	 *
+	 * @param rest5Client the Rest5Client to use
+	 * @return the {@link ElasticsearchClient}
+	 */
+	public static ElasticsearchClient createImperative(Rest5Client rest5Client) {
+		return createImperative(rest5Client, null, DEFAULT_JSONP_MAPPER);
+	}
+
 	/**
 	 * Creates a new imperative {@link ElasticsearchClient}
 	 *
@@ -194,7 +233,9 @@ public final class ElasticsearchClients {
 	 * @param transportOptions options to be added to each request.
 	 * @param jsonpMapper the mapper for the transport to use
 	 * @return the {@link ElasticsearchClient}
+	 * @deprecated since 6.0, use the version with a Rest5Client.
 	 */
+	@Deprecated(since = "6.0", forRemoval = true)
 	public static ElasticsearchClient createImperative(RestClient restClient, @Nullable TransportOptions transportOptions,
 			JsonpMapper jsonpMapper) {
 
@@ -206,6 +247,27 @@ public final class ElasticsearchClients {
 		return createImperative(transport);
 	}
 
+	/**
+	 * Creates a new imperative {@link ElasticsearchClient}
+	 *
+	 * @param rest5Client the Rest5Client to use
+	 * @param transportOptions options to be added to each request.
+	 * @param jsonpMapper the mapper for the transport to use
+	 * @return the {@link ElasticsearchClient}
+	 * @since 6.0
+	 */
+	public static ElasticsearchClient createImperative(Rest5Client rest5Client,
+			@Nullable TransportOptions transportOptions,
+			JsonpMapper jsonpMapper) {
+
+		Assert.notNull(rest5Client, "restClient must not be null");
+
+		ElasticsearchTransport transport = getElasticsearchTransport(rest5Client, IMPERATIVE_CLIENT, transportOptions,
+				jsonpMapper);
+
+		return createImperative(transport);
+	}
+
 	/**
 	 * Creates a new {@link ElasticsearchClient} that uses the given {@link ElasticsearchTransport}.
 	 *
@@ -220,96 +282,6 @@ public final class ElasticsearchClients {
 	}
 	// endregion
 
-	// region low level RestClient
-	private static RestClientOptions.Builder getRestClientOptionsBuilder(@Nullable TransportOptions transportOptions) {
-
-		if (transportOptions instanceof RestClientOptions restClientOptions) {
-			return restClientOptions.toBuilder();
-		}
-
-		var builder = new RestClientOptions.Builder(RequestOptions.DEFAULT.toBuilder());
-
-		if (transportOptions != null) {
-			transportOptions.headers().forEach(header -> builder.addHeader(header.getKey(), header.getValue()));
-			transportOptions.queryParameters().forEach(builder::setParameter);
-			builder.onWarnings(transportOptions.onWarnings());
-		}
-
-		return builder;
-	}
-
-	/**
-	 * Creates a low level {@link RestClient} for the given configuration.
-	 *
-	 * @param clientConfiguration must not be {@literal null}
-	 * @return the {@link RestClient}
-	 */
-	public static RestClient getRestClient(ClientConfiguration clientConfiguration) {
-		return getRestClientBuilder(clientConfiguration).build();
-	}
-
-	private static RestClientBuilder getRestClientBuilder(ClientConfiguration clientConfiguration) {
-		HttpHost[] httpHosts = formattedHosts(clientConfiguration.getEndpoints(), clientConfiguration.useSsl()).stream()
-				.map(HttpHost::create).toArray(HttpHost[]::new);
-		RestClientBuilder builder = RestClient.builder(httpHosts);
-
-		if (clientConfiguration.getPathPrefix() != null) {
-			builder.setPathPrefix(clientConfiguration.getPathPrefix());
-		}
-
-		HttpHeaders headers = clientConfiguration.getDefaultHeaders();
-
-		if (!headers.isEmpty()) {
-			builder.setDefaultHeaders(toHeaderArray(headers));
-		}
-
-		builder.setHttpClientConfigCallback(clientBuilder -> {
-			if (clientConfiguration.getCaFingerprint().isPresent()) {
-				clientBuilder
-						.setSSLContext(TransportUtils.sslContextFromCaFingerprint(clientConfiguration.getCaFingerprint().get()));
-			}
-			clientConfiguration.getSslContext().ifPresent(clientBuilder::setSSLContext);
-			clientConfiguration.getHostNameVerifier().ifPresent(clientBuilder::setSSLHostnameVerifier);
-			clientBuilder.addInterceptorLast(new CustomHeaderInjector(clientConfiguration.getHeadersSupplier()));
-
-			RequestConfig.Builder requestConfigBuilder = RequestConfig.custom();
-			Duration connectTimeout = clientConfiguration.getConnectTimeout();
-
-			if (!connectTimeout.isNegative()) {
-				requestConfigBuilder.setConnectTimeout(Math.toIntExact(connectTimeout.toMillis()));
-			}
-
-			Duration socketTimeout = clientConfiguration.getSocketTimeout();
-
-			if (!socketTimeout.isNegative()) {
-				requestConfigBuilder.setSocketTimeout(Math.toIntExact(socketTimeout.toMillis()));
-				requestConfigBuilder.setConnectionRequestTimeout(Math.toIntExact(socketTimeout.toMillis()));
-			}
-
-			clientBuilder.setDefaultRequestConfig(requestConfigBuilder.build());
-
-			clientConfiguration.getProxy().map(HttpHost::create).ifPresent(clientBuilder::setProxy);
-
-			for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurer : clientConfiguration
-					.getClientConfigurers()) {
-				if (clientConfigurer instanceof ElasticsearchHttpClientConfigurationCallback restClientConfigurationCallback) {
-					clientBuilder = restClientConfigurationCallback.configure(clientBuilder);
-				}
-			}
-
-			return clientBuilder;
-		});
-
-		for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurationCallback : clientConfiguration
-				.getClientConfigurers()) {
-			if (clientConfigurationCallback instanceof ElasticsearchRestClientConfigurationCallback configurationCallback) {
-				builder = configurationCallback.configure(builder);
-			}
-		}
-		return builder;
-	}
-	// endregion
-
 	// region Elasticsearch transport
 	/**
 	 * Creates an {@link ElasticsearchTransport} that will use the given client that additionally is customized with a
@@ -320,7 +292,9 @@ public final class ElasticsearchClients {
 	 * @param transportOptions options for the transport
 	 * @param jsonpMapper mapper for the transport
 	 * @return ElasticsearchTransport
+	 * @deprecated since 6.0, use the version taking a Rest5Client
 	 */
+	@Deprecated(since = "6.0", forRemoval = true)
 	public static ElasticsearchTransport getElasticsearchTransport(RestClient restClient, String clientType,
 			@Nullable TransportOptions transportOptions, JsonpMapper jsonpMapper) {
 
@@ -329,7 +303,7 @@ public final class ElasticsearchClients {
 		Assert.notNull(jsonpMapper, "jsonpMapper must not be null");
 
 		TransportOptions.Builder transportOptionsBuilder = transportOptions != null ? transportOptions.toBuilder()
-				: new RestClientOptions(RequestOptions.DEFAULT, false).toBuilder();
+				: new RestClientOptions(org.elasticsearch.client.RequestOptions.DEFAULT, false).toBuilder();
 
 		RestClientOptions.Builder restClientOptionsBuilder = getRestClientOptionsBuilder(transportOptions);
 
@@ -353,70 +327,35 @@ public final class ElasticsearchClients {
 
 		return new RestClientTransport(restClient, jsonpMapper, restClientOptionsBuilder.build());
 	}
+
+	/**
+	 * Creates an {@link ElasticsearchTransport} that will use the given client that additionally is customized with a
+	 * header to contain the clientType
+	 *
+	 * @param rest5Client the client to use
+	 * @param clientType the client type to pass in each request as header
+	 * @param transportOptions options for the transport
+	 * @param jsonpMapper mapper for the transport
+	 * @return ElasticsearchTransport
+	 */
+	public static ElasticsearchTransport getElasticsearchTransport(Rest5Client rest5Client, String clientType,
+			@Nullable TransportOptions transportOptions, JsonpMapper jsonpMapper) {
+
+		Assert.notNull(rest5Client, "restClient must not be null");
+		Assert.notNull(clientType, "clientType must not be null");
+		Assert.notNull(jsonpMapper, "jsonpMapper must not be null");
+
+		TransportOptions.Builder transportOptionsBuilder = transportOptions != null ? transportOptions.toBuilder()
+				: new Rest5ClientOptions(RequestOptions.DEFAULT, false).toBuilder();
+
+		Rest5ClientOptions.Builder rest5ClientOptionsBuilder = getRest5ClientOptionsBuilder(transportOptions);
+
+		rest5ClientOptionsBuilder.addHeader(X_SPRING_DATA_ELASTICSEARCH_CLIENT,
+				VersionInfo.clientVersions() + " / " + clientType);
+
+		return new Rest5ClientTransport(rest5Client, jsonpMapper, rest5ClientOptionsBuilder.build());
+	}
 	// endregion
 
-	private static List<String> formattedHosts(List<InetSocketAddress> hosts, boolean useSsl) {
-		return hosts.stream().map(it -> (useSsl ? "https" : "http") + "://" + it.getHostString() + ':' + it.getPort())
-				.collect(Collectors.toList());
-	}
-
-	private static org.apache.http.Header[] toHeaderArray(HttpHeaders headers) {
-		return headers.entrySet().stream() //
-				.flatMap(entry -> entry.getValue().stream() //
-						.map(value -> new BasicHeader(entry.getKey(), value))) //
-				.toArray(org.apache.http.Header[]::new);
-	}
-
-	/**
-	 * Interceptor to inject custom supplied headers.
-	 *
-	 * @since 4.4
-	 */
-	private record CustomHeaderInjector(Supplier<HttpHeaders> headersSupplier) implements HttpRequestInterceptor {
-
-		@Override
-		public void process(HttpRequest request, HttpContext context) {
-			HttpHeaders httpHeaders = headersSupplier.get();
-
-			if (httpHeaders != null && !httpHeaders.isEmpty()) {
-				Arrays.stream(toHeaderArray(httpHeaders)).forEach(request::addHeader);
-			}
-		}
-	}
-
-	/**
-	 * {@link org.springframework.data.elasticsearch.client.ClientConfiguration.ClientConfigurationCallback} to configure
-	 * the Elasticsearch RestClient's Http client with a {@link HttpAsyncClientBuilder}
-	 *
-	 * @since 4.4
-	 */
-	public interface ElasticsearchHttpClientConfigurationCallback
-			extends ClientConfiguration.ClientConfigurationCallback<HttpAsyncClientBuilder> {
-
-		static ElasticsearchHttpClientConfigurationCallback from(
-				Function<HttpAsyncClientBuilder, HttpAsyncClientBuilder> httpClientBuilderCallback) {
-
-			Assert.notNull(httpClientBuilderCallback, "httpClientBuilderCallback must not be null");
-
-			return httpClientBuilderCallback::apply;
-		}
-	}
-
-	/**
-	 * {@link org.springframework.data.elasticsearch.client.ClientConfiguration.ClientConfigurationCallback} to configure
-	 * the RestClient client with a {@link RestClientBuilder}
-	 *
-	 * @since 5.0
-	 */
-	public interface ElasticsearchRestClientConfigurationCallback
-			extends ClientConfiguration.ClientConfigurationCallback<RestClientBuilder> {
-
-		static ElasticsearchRestClientConfigurationCallback from(
-				Function<RestClientBuilder, RestClientBuilder> restClientBuilderCallback) {
-
-			Assert.notNull(restClientBuilderCallback, "restClientBuilderCallback must not be null");
-
-			return restClientBuilderCallback::apply;
-		}
-	}
+	// todo #3117 remove and document that ElasticsearchHttpClientConfigurationCallback has been move to RestClients.
 }

src/main/java/org/springframework/data/elasticsearch/client/elc/ElasticsearchConfiguration.java

@@ -20,12 +20,13 @@ import co.elastic.clients.json.JsonpMapper;
 import co.elastic.clients.json.jackson.JacksonJsonpMapper;
 import co.elastic.clients.transport.ElasticsearchTransport;
 import co.elastic.clients.transport.TransportOptions;
-import co.elastic.clients.transport.rest_client.RestClientOptions;
+import co.elastic.clients.transport.rest5_client.Rest5ClientOptions;
+import co.elastic.clients.transport.rest5_client.low_level.RequestOptions;
+import co.elastic.clients.transport.rest5_client.low_level.Rest5Client;
 
-import org.elasticsearch.client.RequestOptions;
-import org.elasticsearch.client.RestClient;
 import org.springframework.context.annotation.Bean;
 import org.springframework.data.elasticsearch.client.ClientConfiguration;
+import org.springframework.data.elasticsearch.client.elc.rest5_client.Rest5Clients;
 import org.springframework.data.elasticsearch.config.ElasticsearchConfigurationSupport;
 import org.springframework.data.elasticsearch.core.ElasticsearchOperations;
 import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
@@ -38,7 +39,9 @@ import com.fasterxml.jackson.databind.SerializationFeature;
 /**
  * Base class for a @{@link org.springframework.context.annotation.Configuration} class to set up the Elasticsearch
  * connection using the Elasticsearch Client. This class exposes different parts of the setup as Spring beans. Deriving
- * classes must provide the {@link ClientConfiguration} to use.
+ * classes must provide the {@link ClientConfiguration} to use. From Version 6.0 on, this class uses the new Rest5Client
+ * from Elasticsearch 9. The old implementation using the RestClient is still available under the name
+ * {@link ElasticsearchLegacyRestClientConfiguration}.
  *
  * @author Peter-Josef Meisch
  * @since 4.4
@@ -60,27 +63,27 @@ public abstract class ElasticsearchConfiguration extends ElasticsearchConfigurat
 	 * @return RestClient
 	 */
 	@Bean
-	public RestClient elasticsearchRestClient(ClientConfiguration clientConfiguration) {
+	public Rest5Client elasticsearchRest5Client(ClientConfiguration clientConfiguration) {
 
 		Assert.notNull(clientConfiguration, "clientConfiguration must not be null");
 
-		return ElasticsearchClients.getRestClient(clientConfiguration);
+		return Rest5Clients.getRest5Client(clientConfiguration);
 	}
 
 	/**
-	 * Provides the Elasticsearch transport to be used. The default implementation uses the {@link RestClient} bean and
+	 * Provides the Elasticsearch transport to be used. The default implementation uses the {@link Rest5Client} bean and
 	 * the {@link JsonpMapper} bean provided in this class.
 	 *
 	 * @return the {@link ElasticsearchTransport}
 	 * @since 5.2
 	 */
 	@Bean
-	public ElasticsearchTransport elasticsearchTransport(RestClient restClient, JsonpMapper jsonpMapper) {
+	public ElasticsearchTransport elasticsearchTransport(Rest5Client rest5Client, JsonpMapper jsonpMapper) {
 
-		Assert.notNull(restClient, "restClient must not be null");
+		Assert.notNull(rest5Client, "restClient must not be null");
 		Assert.notNull(jsonpMapper, "jsonpMapper must not be null");
 
-		return ElasticsearchClients.getElasticsearchTransport(restClient, ElasticsearchClients.IMPERATIVE_CLIENT,
+		return ElasticsearchClients.getElasticsearchTransport(rest5Client, ElasticsearchClients.IMPERATIVE_CLIENT,
 				transportOptions(), jsonpMapper);
 	}
 
@@ -115,7 +118,7 @@ public abstract class ElasticsearchConfiguration extends ElasticsearchConfigurat
 	}
 
 	/**
-	 * Provides the JsonpMapper bean that is used in the {@link #elasticsearchTransport(RestClient, JsonpMapper)} method.
+	 * Provides the JsonpMapper bean that is used in the {@link #elasticsearchTransport(Rest5Client, JsonpMapper)} method.
 	 *
 	 * @return the {@link JsonpMapper} to use
 	 * @since 5.2
@@ -135,6 +138,6 @@ public abstract class ElasticsearchConfiguration extends ElasticsearchConfigurat
 	 * @return the options that should be added to every request. Must not be {@literal null}
 	 */
 	public TransportOptions transportOptions() {
-		return new RestClientOptions(RequestOptions.DEFAULT, false);
+		return new Rest5ClientOptions(RequestOptions.DEFAULT, false);
 	}
 }

src/main/java/org/springframework/data/elasticsearch/client/elc/ElasticsearchExceptionTranslator.java

@@ -119,14 +119,19 @@ public class ElasticsearchExceptionTranslator implements PersistenceExceptionTra
 		String message = null;
 
 		if (exception instanceof ResponseException responseException) {
+			// this code is for the old RestClient
 			status = responseException.getResponse().getStatusLine().getStatusCode();
 			message = responseException.getMessage();
+		} else if (exception instanceof ElasticsearchException elasticsearchException) {
+			// using the RestClient throws this
+			status = elasticsearchException.status();
+			message = elasticsearchException.getMessage();
 		} else if (exception.getCause() != null) {
 			checkForConflictException(exception.getCause());
 		}
 
 		if (status != null && message != null) {
-			if (status == 409 && message.contains("type\":\"version_conflict_engine_exception"))
+			if (status == 409 && message.contains("version_conflict_engine_exception"))
 				if (message.contains("version conflict, required seqNo")) {
 					throw new OptimisticLockingFailureException("Cannot index a document due to seq_no+primary_term conflict",
 							exception);

src/main/java/org/springframework/data/elasticsearch/client/elc/ElasticsearchLegacyRestClientConfiguration.java

@@ -0,0 +1,144 @@
+/*
+ * Copyright 2021-2025 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.data.elasticsearch.client.elc;
+
+import co.elastic.clients.elasticsearch.ElasticsearchClient;
+import co.elastic.clients.json.JsonpMapper;
+import co.elastic.clients.json.jackson.JacksonJsonpMapper;
+import co.elastic.clients.transport.ElasticsearchTransport;
+import co.elastic.clients.transport.TransportOptions;
+import co.elastic.clients.transport.rest_client.RestClientOptions;
+
+import org.elasticsearch.client.RequestOptions;
+import org.elasticsearch.client.RestClient;
+import org.springframework.context.annotation.Bean;
+import org.springframework.data.elasticsearch.client.ClientConfiguration;
+import org.springframework.data.elasticsearch.client.elc.rest_client.RestClients;
+import org.springframework.data.elasticsearch.config.ElasticsearchConfigurationSupport;
+import org.springframework.data.elasticsearch.core.ElasticsearchOperations;
+import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
+import org.springframework.util.Assert;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
+
+/**
+ * Base class for a @{@link org.springframework.context.annotation.Configuration} class to set up the Elasticsearch
+ * connection using the Elasticsearch Client. This class exposes different parts of the setup as Spring beans. Deriving
+ * classes must provide the {@link ClientConfiguration} to use. <br/>
+ * This class uses the Elasticsearch RestClient which was replaced by the Rest5Client in Elasticsearch 9. It is still
+ * available here but deprecated.
+ *
+ * @author Peter-Josef Meisch
+ * @since 4.4
+ * @deprecated since 6.0, use {@link ElasticsearchConfiguration}
+ */
+@Deprecated(since = "6.0", forRemoval=true)
+public abstract class ElasticsearchLegacyRestClientConfiguration extends ElasticsearchConfigurationSupport {
+
+	/**
+	 * Must be implemented by deriving classes to provide the {@link ClientConfiguration}.
+	 *
+	 * @return configuration, must not be {@literal null}
+	 */
+	@Bean(name = "elasticsearchClientConfiguration")
+	public abstract ClientConfiguration clientConfiguration();
+
+	/**
+	 * Provides the underlying low level Elasticsearch RestClient.
+	 *
+	 * @param clientConfiguration configuration for the client, must not be {@literal null}
+	 * @return RestClient
+	 */
+	@Bean
+	public RestClient elasticsearchRestClient(ClientConfiguration clientConfiguration) {
+
+		Assert.notNull(clientConfiguration, "clientConfiguration must not be null");
+
+		return RestClients.getRestClient(clientConfiguration);
+	}
+
+	/**
+	 * Provides the Elasticsearch transport to be used. The default implementation uses the {@link RestClient} bean and
+	 * the {@link JsonpMapper} bean provided in this class.
+	 *
+	 * @return the {@link ElasticsearchTransport}
+	 * @since 5.2
+	 */
+	@Bean
+	public ElasticsearchTransport elasticsearchTransport(RestClient restClient, JsonpMapper jsonpMapper) {
+
+		Assert.notNull(restClient, "restClient must not be null");
+		Assert.notNull(jsonpMapper, "jsonpMapper must not be null");
+
+		return ElasticsearchClients.getElasticsearchTransport(restClient, ElasticsearchClients.IMPERATIVE_CLIENT,
+				transportOptions(), jsonpMapper);
+	}
+
+	/**
+	 * Provides the {@link ElasticsearchClient} to be used.
+	 *
+	 * @param transport the {@link ElasticsearchTransport} to use
+	 * @return ElasticsearchClient instance
+	 */
+	@Bean
+	public ElasticsearchClient elasticsearchClient(ElasticsearchTransport transport) {
+
+		Assert.notNull(transport, "transport must not be null");
+
+		return ElasticsearchClients.createImperative(transport);
+	}
+
+	/**
+	 * Creates a {@link ElasticsearchOperations} implementation using an {@link ElasticsearchClient}.
+	 *
+	 * @return never {@literal null}.
+	 */
+	@Bean(name = { "elasticsearchOperations", "elasticsearchTemplate" })
+	public ElasticsearchOperations elasticsearchOperations(ElasticsearchConverter elasticsearchConverter,
+			ElasticsearchClient elasticsearchClient) {
+
+		ElasticsearchTemplate template = new ElasticsearchTemplate(elasticsearchClient, elasticsearchConverter);
+		template.setRefreshPolicy(refreshPolicy());
+
+		return template;
+	}
+
+	/**
+	 * Provides the JsonpMapper bean that is used in the {@link #elasticsearchTransport(RestClient, JsonpMapper)} method.
+	 *
+	 * @return the {@link JsonpMapper} to use
+	 * @since 5.2
+	 */
+	@Bean
+	public JsonpMapper jsonpMapper() {
+		// we need to create our own objectMapper that keeps null values in order to provide the storeNullValue
+		// functionality. The one Elasticsearch would provide removes the nulls. We remove unwanted nulls before they get
+		// into this mapper, so we can safely keep them here.
+		var objectMapper = (new ObjectMapper())
+				.configure(SerializationFeature.INDENT_OUTPUT, false)
+				.setSerializationInclusion(JsonInclude.Include.ALWAYS);
+		return new JacksonJsonpMapper(objectMapper);
+	}
+
+	/**
+	 * @return the options that should be added to every request. Must not be {@literal null}
+	 */
+	public TransportOptions transportOptions() {
+		return new RestClientOptions(RequestOptions.DEFAULT, false);
+	}
+}

src/main/java/org/springframework/data/elasticsearch/client/elc/ElasticsearchTemplate.java

@@ -40,6 +40,7 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.BulkFailureException;
 import org.springframework.data.elasticsearch.client.UnsupportedBackendOperation;
 import org.springframework.data.elasticsearch.core.AbstractElasticsearchTemplate;
@@ -59,7 +60,6 @@ import org.springframework.data.elasticsearch.core.reindex.ReindexRequest;
 import org.springframework.data.elasticsearch.core.reindex.ReindexResponse;
 import org.springframework.data.elasticsearch.core.script.Script;
 import org.springframework.data.elasticsearch.core.sql.SqlResponse;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/client/elc/HighlightQueryBuilder.java

@@ -20,6 +20,7 @@ import static org.springframework.data.elasticsearch.client.elc.TypeUtils.*;
 import java.util.Arrays;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.mapping.ElasticsearchPersistentEntity;
 import org.springframework.data.elasticsearch.core.mapping.ElasticsearchPersistentProperty;
 import org.springframework.data.elasticsearch.core.query.highlight.Highlight;
@@ -27,7 +28,6 @@ import org.springframework.data.elasticsearch.core.query.highlight.HighlightFiel
 import org.springframework.data.elasticsearch.core.query.highlight.HighlightFieldParameters;
 import org.springframework.data.elasticsearch.core.query.highlight.HighlightParameters;
 import org.springframework.data.mapping.context.MappingContext;
-import org.springframework.lang.Nullable;
 import org.springframework.util.StringUtils;
 
 /**
@@ -43,7 +43,8 @@ class HighlightQueryBuilder {
 	private final RequestConverter requestConverter;
 
 	HighlightQueryBuilder(
-			MappingContext<? extends ElasticsearchPersistentEntity<?>, ElasticsearchPersistentProperty> mappingContext, RequestConverter requestConverter) {
+			MappingContext<? extends ElasticsearchPersistentEntity<?>, ElasticsearchPersistentProperty> mappingContext,
+			RequestConverter requestConverter) {
 		this.mappingContext = mappingContext;
 		this.requestConverter = requestConverter;
 	}

src/main/java/org/springframework/data/elasticsearch/client/elc/IndicesTemplate.java

@@ -27,6 +27,7 @@ import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.elasticsearch.UncategorizedElasticsearchException;
@@ -49,7 +50,6 @@ import org.springframework.data.elasticsearch.core.mapping.Alias;
 import org.springframework.data.elasticsearch.core.mapping.CreateIndexSettings;
 import org.springframework.data.elasticsearch.core.mapping.ElasticsearchPersistentEntity;
 import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/client/elc/JsonUtils.java

@@ -23,7 +23,7 @@ import java.nio.charset.StandardCharsets;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * @author Peter-Josef Meisch
@@ -48,7 +48,7 @@ final class JsonUtils {
 	}
 
 	@Nullable
-	public static String queryToJson(@Nullable co.elastic.clients.elasticsearch._types.query_dsl.Query query,
+	public static String queryToJson(co.elastic.clients.elasticsearch._types.query_dsl.@Nullable Query query,
 			JsonpMapper mapper) {
 
 		if (query == null) {

src/main/java/org/springframework/data/elasticsearch/client/elc/NativeQuery.java

@@ -28,8 +28,8 @@ import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.query.BaseQuery;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -44,7 +44,7 @@ import org.springframework.util.Assert;
 public class NativeQuery extends BaseQuery {
 
 	@Nullable private final Query query;
-	@Nullable private org.springframework.data.elasticsearch.core.query.Query springDataQuery;
+	private org.springframework.data.elasticsearch.core.query.@Nullable Query springDataQuery;
 	@Nullable private Query filter;
 	// note: the new client does not have pipeline aggs, these are just set up as normal aggs
 	private final Map<String, Aggregation> aggregations = new LinkedHashMap<>();
@@ -117,7 +117,7 @@ public class NativeQuery extends BaseQuery {
 	 * @see NativeQueryBuilder#withQuery(org.springframework.data.elasticsearch.core.query.Query).
 	 * @since 5.1
 	 */
-	public void setSpringDataQuery(@Nullable org.springframework.data.elasticsearch.core.query.Query springDataQuery) {
+	public void setSpringDataQuery(org.springframework.data.elasticsearch.core.query.@Nullable Query springDataQuery) {
 		this.springDataQuery = springDataQuery;
 	}
 
@@ -129,8 +129,7 @@ public class NativeQuery extends BaseQuery {
 		return knnSearches;
 	}
 
-	@Nullable
-	public org.springframework.data.elasticsearch.core.query.Query getSpringDataQuery() {
+	public org.springframework.data.elasticsearch.core.query.@Nullable Query getSpringDataQuery() {
 		return springDataQuery;
 	}
 }

src/main/java/org/springframework/data/elasticsearch/client/elc/NativeQueryBuilder.java

@@ -33,8 +33,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.query.BaseQueryBuilder;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -53,7 +53,7 @@ public class NativeQueryBuilder extends BaseQueryBuilder<NativeQuery, NativeQuer
 	private final List<SortOptions> sortOptions = new ArrayList<>();
 	private final Map<String, JsonData> searchExtensions = new LinkedHashMap<>();
 
-	@Nullable private org.springframework.data.elasticsearch.core.query.Query springDataQuery;
+	private org.springframework.data.elasticsearch.core.query.@Nullable Query springDataQuery;
 	@Nullable private KnnQuery knnQuery;
 	@Nullable private List<KnnSearch> knnSearches = Collections.emptyList();
 
@@ -104,8 +104,7 @@ public class NativeQueryBuilder extends BaseQueryBuilder<NativeQuery, NativeQuer
 		return knnSearches;
 	}
 
-	@Nullable
-	public org.springframework.data.elasticsearch.core.query.Query getSpringDataQuery() {
+	public org.springframework.data.elasticsearch.core.query.@Nullable Query getSpringDataQuery() {
 		return springDataQuery;
 	}
 

src/main/java/org/springframework/data/elasticsearch/client/elc/Queries.java

@@ -34,9 +34,9 @@ import java.util.Base64;
 import java.util.List;
 import java.util.function.Function;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.geo.GeoPoint;
 import org.springframework.data.elasticsearch.core.query.BaseQueryBuilder;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/client/elc/ReactiveElasticsearchClient.java

@@ -30,7 +30,7 @@ import reactor.core.publisher.Mono;
 import java.io.IOException;
 import java.util.function.Function;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/client/elc/ReactiveElasticsearchClusterClient.java

@@ -16,7 +16,15 @@
 package org.springframework.data.elasticsearch.client.elc;
 
 import co.elastic.clients.ApiClient;
-import co.elastic.clients.elasticsearch.cluster.*;
+import co.elastic.clients.elasticsearch.cluster.DeleteComponentTemplateRequest;
+import co.elastic.clients.elasticsearch.cluster.DeleteComponentTemplateResponse;
+import co.elastic.clients.elasticsearch.cluster.ExistsComponentTemplateRequest;
+import co.elastic.clients.elasticsearch.cluster.GetComponentTemplateRequest;
+import co.elastic.clients.elasticsearch.cluster.GetComponentTemplateResponse;
+import co.elastic.clients.elasticsearch.cluster.HealthRequest;
+import co.elastic.clients.elasticsearch.cluster.HealthResponse;
+import co.elastic.clients.elasticsearch.cluster.PutComponentTemplateRequest;
+import co.elastic.clients.elasticsearch.cluster.PutComponentTemplateResponse;
 import co.elastic.clients.transport.ElasticsearchTransport;
 import co.elastic.clients.transport.TransportOptions;
 import co.elastic.clients.transport.endpoints.BooleanResponse;
@@ -25,7 +33,7 @@ import reactor.core.publisher.Mono;
 
 import java.util.function.Function;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Reactive version of the {@link co.elastic.clients.elasticsearch.cluster.ElasticsearchClusterClient}

src/main/java/org/springframework/data/elasticsearch/client/elc/ReactiveElasticsearchConfiguration.java

@@ -19,12 +19,18 @@ import co.elastic.clients.json.JsonpMapper;
 import co.elastic.clients.json.jackson.JacksonJsonpMapper;
 import co.elastic.clients.transport.ElasticsearchTransport;
 import co.elastic.clients.transport.TransportOptions;
+import co.elastic.clients.transport.rest5_client.Rest5ClientOptions;
+import co.elastic.clients.transport.rest5_client.low_level.RequestOptions;
+import co.elastic.clients.transport.rest5_client.low_level.Rest5Client;
 import co.elastic.clients.transport.rest_client.RestClientOptions;
 
-import org.elasticsearch.client.RequestOptions;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
 import org.elasticsearch.client.RestClient;
 import org.springframework.context.annotation.Bean;
 import org.springframework.data.elasticsearch.client.ClientConfiguration;
+import org.springframework.data.elasticsearch.client.elc.rest5_client.Rest5Clients;
 import org.springframework.data.elasticsearch.config.ElasticsearchConfigurationSupport;
 import org.springframework.data.elasticsearch.core.ReactiveElasticsearchOperations;
 import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
@@ -55,11 +61,11 @@ public abstract class ReactiveElasticsearchConfiguration extends ElasticsearchCo
 	 * @return RestClient
 	 */
 	@Bean
-	public RestClient elasticsearchRestClient(ClientConfiguration clientConfiguration) {
+	public Rest5Client elasticsearchRestClient(ClientConfiguration clientConfiguration) {
 
 		Assert.notNull(clientConfiguration, "clientConfiguration must not be null");
 
-		return ElasticsearchClients.getRestClient(clientConfiguration);
+		return Rest5Clients.getRest5Client(clientConfiguration);
 	}
 
 	/**
@@ -70,12 +76,12 @@ public abstract class ReactiveElasticsearchConfiguration extends ElasticsearchCo
 	 * @since 5.2
 	 */
 	@Bean
-	public ElasticsearchTransport elasticsearchTransport(RestClient restClient, JsonpMapper jsonpMapper) {
+	public ElasticsearchTransport elasticsearchTransport(Rest5Client rest5Client, JsonpMapper jsonpMapper) {
 
-		Assert.notNull(restClient, "restClient must not be null");
+		Assert.notNull(rest5Client, "restClient must not be null");
 		Assert.notNull(jsonpMapper, "jsonpMapper must not be null");
 
-		return ElasticsearchClients.getElasticsearchTransport(restClient, ElasticsearchClients.REACTIVE_CLIENT,
+		return ElasticsearchClients.getElasticsearchTransport(rest5Client, ElasticsearchClients.REACTIVE_CLIENT,
 				transportOptions(), jsonpMapper);
 	}
 
@@ -110,7 +116,7 @@ public abstract class ReactiveElasticsearchConfiguration extends ElasticsearchCo
 	}
 
 	/**
-	 * Provides the JsonpMapper that is used in the {@link #elasticsearchTransport(RestClient, JsonpMapper)} method and
+	 * Provides the JsonpMapper that is used in the {@link #elasticsearchTransport(Rest5Client, JsonpMapper)} method and
 	 * exposes it as a bean.
 	 *
 	 * @return the {@link JsonpMapper} to use
@@ -118,13 +124,19 @@ public abstract class ReactiveElasticsearchConfiguration extends ElasticsearchCo
 	 */
 	@Bean
 	public JsonpMapper jsonpMapper() {
-		return new JacksonJsonpMapper();
+		// we need to create our own objectMapper that keeps null values in order to provide the storeNullValue
+		// functionality. The one Elasticsearch would provide removes the nulls. We remove unwanted nulls before they get
+		// into this mapper, so we can safely keep them here.
+		var objectMapper = (new ObjectMapper())
+				.configure(SerializationFeature.INDENT_OUTPUT, false)
+				.setSerializationInclusion(JsonInclude.Include.ALWAYS);
+		return new JacksonJsonpMapper(objectMapper);
 	}
 
 	/**
 	 * @return the options that should be added to every request. Must not be {@literal null}
 	 */
 	public TransportOptions transportOptions() {
-		return new RestClientOptions(RequestOptions.DEFAULT, false).toBuilder().build();
+		return new Rest5ClientOptions(RequestOptions.DEFAULT, false);
 	}
 }

src/main/java/org/springframework/data/elasticsearch/client/elc/ReactiveElasticsearchIndicesClient.java

@@ -25,7 +25,7 @@ import reactor.core.publisher.Mono;
 
 import java.util.function.Function;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Reactive version of the {@link co.elastic.clients.elasticsearch.indices.ElasticsearchIndicesClient}
@@ -539,14 +539,6 @@ public class ReactiveElasticsearchIndicesClient
 		return stats(builder -> builder);
 	}
 
-	public Mono<UnfreezeResponse> unfreeze(UnfreezeRequest request) {
-		return Mono.fromFuture(transport.performRequestAsync(request, UnfreezeRequest._ENDPOINT, transportOptions));
-	}
-
-	public Mono<UnfreezeResponse> unfreeze(Function<UnfreezeRequest.Builder, ObjectBuilder<UnfreezeRequest>> fn) {
-		return unfreeze(fn.apply(new UnfreezeRequest.Builder()).build());
-	}
-
 	public Mono<UpdateAliasesResponse> updateAliases(UpdateAliasesRequest request) {
 		return Mono.fromFuture(transport.performRequestAsync(request, UpdateAliasesRequest._ENDPOINT, transportOptions));
 	}

src/main/java/org/springframework/data/elasticsearch/client/elc/ReactiveElasticsearchLegacyRestClientConfiguration.java

@@ -0,0 +1,144 @@
+/*
+ * Copyright 2021-2025 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.data.elasticsearch.client.elc;
+
+import co.elastic.clients.json.JsonpMapper;
+import co.elastic.clients.json.jackson.JacksonJsonpMapper;
+import co.elastic.clients.transport.ElasticsearchTransport;
+import co.elastic.clients.transport.TransportOptions;
+import co.elastic.clients.transport.rest_client.RestClientOptions;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
+import org.elasticsearch.client.RequestOptions;
+import org.elasticsearch.client.RestClient;
+import org.springframework.context.annotation.Bean;
+import org.springframework.data.elasticsearch.client.ClientConfiguration;
+import org.springframework.data.elasticsearch.client.elc.rest_client.RestClients;
+import org.springframework.data.elasticsearch.config.ElasticsearchConfigurationSupport;
+import org.springframework.data.elasticsearch.core.ReactiveElasticsearchOperations;
+import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
+import org.springframework.util.Assert;
+
+/**
+ * Base class for a @{@link org.springframework.context.annotation.Configuration} class to set up the Elasticsearch
+ * connection using the {@link ReactiveElasticsearchClient}. This class exposes different parts of the setup as Spring
+ * beans. Deriving * classes must provide the {@link ClientConfiguration} to use. <br/>
+ * This class uses the Elasticsearch RestClient which was replaced b y the Rest5Client in Elasticsearch 9. It is still
+ * available here but deprecated. *
+ *
+ * @author Peter-Josef Meisch
+ * @since 4.4
+ * @deprecated since 6.0 use {@link ReactiveElasticsearchConfiguration}
+ */
+@Deprecated(since = "6.0", forRemoval=true)
+public abstract class ReactiveElasticsearchLegacyRestClientConfiguration extends ElasticsearchConfigurationSupport {
+
+	/**
+	 * Must be implemented by deriving classes to provide the {@link ClientConfiguration}.
+	 *
+	 * @return configuration, must not be {@literal null}
+	 */
+	@Bean(name = "elasticsearchClientConfiguration")
+	public abstract ClientConfiguration clientConfiguration();
+
+	/**
+	 * Provides the underlying low level RestClient.
+	 *
+	 * @param clientConfiguration configuration for the client, must not be {@literal null}
+	 * @return RestClient
+	 */
+	@Bean
+	public RestClient elasticsearchRestClient(ClientConfiguration clientConfiguration) {
+
+		Assert.notNull(clientConfiguration, "clientConfiguration must not be null");
+
+		return RestClients.getRestClient(clientConfiguration);
+	}
+
+	/**
+	 * Provides the Elasticsearch transport to be used. The default implementation uses the {@link RestClient} bean and
+	 * the {@link JsonpMapper} bean provided in this class.
+	 *
+	 * @return the {@link ElasticsearchTransport}
+	 * @since 5.2
+	 */
+	@Bean
+	public ElasticsearchTransport elasticsearchTransport(RestClient restClient, JsonpMapper jsonpMapper) {
+
+		Assert.notNull(restClient, "restClient must not be null");
+		Assert.notNull(jsonpMapper, "jsonpMapper must not be null");
+
+		return ElasticsearchClients.getElasticsearchTransport(restClient, ElasticsearchClients.REACTIVE_CLIENT,
+				transportOptions(), jsonpMapper);
+	}
+
+	/**
+	 * Provides the {@link ReactiveElasticsearchClient} instance used.
+	 *
+	 * @param transport the ElasticsearchTransport to use
+	 * @return ReactiveElasticsearchClient instance.
+	 */
+	@Bean
+	public ReactiveElasticsearchClient reactiveElasticsearchClient(ElasticsearchTransport transport) {
+
+		Assert.notNull(transport, "transport must not be null");
+
+		return ElasticsearchClients.createReactive(transport);
+	}
+
+	/**
+	 * Creates {@link ReactiveElasticsearchOperations}.
+	 *
+	 * @return never {@literal null}.
+	 */
+	@Bean(name = { "reactiveElasticsearchOperations", "reactiveElasticsearchTemplate" })
+	public ReactiveElasticsearchOperations reactiveElasticsearchOperations(ElasticsearchConverter elasticsearchConverter,
+			ReactiveElasticsearchClient reactiveElasticsearchClient) {
+
+		ReactiveElasticsearchTemplate template = new ReactiveElasticsearchTemplate(reactiveElasticsearchClient,
+				elasticsearchConverter);
+		template.setRefreshPolicy(refreshPolicy());
+
+		return template;
+	}
+
+	/**
+	 * Provides the JsonpMapper that is used in the {@link #elasticsearchTransport(RestClient, JsonpMapper)} method and
+	 * exposes it as a bean.
+	 *
+	 * @return the {@link JsonpMapper} to use
+	 * @since 5.2
+	 */
+	@Bean
+	public JsonpMapper jsonpMapper() {
+		// we need to create our own objectMapper that keeps null values in order to provide the storeNullValue
+		// functionality. The one Elasticsearch would provide removes the nulls. We remove unwanted nulls before they get
+		// into this mapper, so we can safely keep them here.
+		var objectMapper = (new ObjectMapper())
+				.configure(SerializationFeature.INDENT_OUTPUT, false)
+				.setSerializationInclusion(JsonInclude.Include.ALWAYS);
+		return new JacksonJsonpMapper(objectMapper);
+	}
+
+	/**
+	 * @return the options that should be added to every request. Must not be {@literal null}
+	 */
+	public TransportOptions transportOptions() {
+		return new RestClientOptions(RequestOptions.DEFAULT, false).toBuilder().build();
+	}
+}

src/main/java/org/springframework/data/elasticsearch/client/elc/ReactiveElasticsearchTemplate.java

@@ -40,6 +40,7 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Publisher;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.elasticsearch.BulkFailureException;
@@ -63,7 +64,6 @@ import org.springframework.data.elasticsearch.core.reindex.ReindexRequest;
 import org.springframework.data.elasticsearch.core.reindex.ReindexResponse;
 import org.springframework.data.elasticsearch.core.script.Script;
 import org.springframework.data.elasticsearch.core.sql.SqlResponse;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;

src/main/java/org/springframework/data/elasticsearch/client/elc/ReactiveIndicesTemplate.java

@@ -29,6 +29,7 @@ import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.elasticsearch.NoSuchIndexException;
@@ -51,7 +52,6 @@ import org.springframework.data.elasticsearch.core.mapping.Alias;
 import org.springframework.data.elasticsearch.core.mapping.CreateIndexSettings;
 import org.springframework.data.elasticsearch.core.mapping.ElasticsearchPersistentEntity;
 import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/client/elc/RequestConverter.java

@@ -42,10 +42,10 @@ import co.elastic.clients.elasticsearch.core.bulk.CreateOperation;
 import co.elastic.clients.elasticsearch.core.bulk.IndexOperation;
 import co.elastic.clients.elasticsearch.core.bulk.UpdateOperation;
 import co.elastic.clients.elasticsearch.core.mget.MultiGetOperation;
-import co.elastic.clients.elasticsearch.core.msearch.MultisearchBody;
 import co.elastic.clients.elasticsearch.core.msearch.MultisearchHeader;
 import co.elastic.clients.elasticsearch.core.search.Highlight;
 import co.elastic.clients.elasticsearch.core.search.Rescore;
+import co.elastic.clients.elasticsearch.core.search.SearchRequestBody;
 import co.elastic.clients.elasticsearch.core.search.SourceConfig;
 import co.elastic.clients.elasticsearch.indices.*;
 import co.elastic.clients.elasticsearch.indices.ExistsIndexTemplateRequest;
@@ -55,6 +55,7 @@ import co.elastic.clients.elasticsearch.sql.query.SqlFormat;
 import co.elastic.clients.json.JsonData;
 import co.elastic.clients.json.JsonpDeserializer;
 import co.elastic.clients.json.JsonpMapper;
+import co.elastic.clients.util.NamedValue;
 import co.elastic.clients.util.ObjectBuilder;
 import jakarta.json.stream.JsonParser;
 
@@ -72,10 +73,12 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.function.Function;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.Nullable;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.elasticsearch.core.RefreshPolicy;
@@ -99,7 +102,6 @@ import org.springframework.data.elasticsearch.core.reindex.ReindexRequest;
 import org.springframework.data.elasticsearch.core.reindex.Remote;
 import org.springframework.data.elasticsearch.core.script.Script;
 import org.springframework.data.elasticsearch.support.DefaultStringObjectMap;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
@@ -118,9 +120,6 @@ class RequestConverter extends AbstractQueryProcessor {
 
 	private static final Log LOGGER = LogFactory.getLog(RequestConverter.class);
 
-	// the default max result window size of Elasticsearch
-	public static final Integer INDEX_MAX_RESULT_WINDOW = 10_000;
-
 	protected final JsonpMapper jsonpMapper;
 	protected final ElasticsearchConverter elasticsearchConverter;
 
@@ -724,20 +723,18 @@ class RequestConverter extends AbstractQueryProcessor {
 			return a;
 		});
 
-		uob //
-				.routing(query.getRouting()) //
-				.ifSeqNo(query.getIfSeqNo() != null ? Long.valueOf(query.getIfSeqNo()) : null) //
-				.ifPrimaryTerm(query.getIfPrimaryTerm() != null ? Long.valueOf(query.getIfPrimaryTerm()) : null) //
-				.retryOnConflict(query.getRetryOnConflict()) //
-		;
+		uob
+				.routing(query.getRouting())
+				.ifSeqNo(query.getIfSeqNo())
+				.ifPrimaryTerm(query.getIfPrimaryTerm())
+				.retryOnConflict(query.getRetryOnConflict());
 
 		// no refresh, timeout, waitForActiveShards on UpdateOperation or UpdateAction
 
 		return uob.build();
 	}
 
-	@Nullable
-	private co.elastic.clients.elasticsearch._types.Script getScript(@Nullable ScriptData scriptData) {
+	private co.elastic.clients.elasticsearch._types.@Nullable Script getScript(@Nullable ScriptData scriptData) {
 
 		if (scriptData == null) {
 			return null;
@@ -750,11 +747,10 @@ class RequestConverter extends AbstractQueryProcessor {
 		}
 		return co.elastic.clients.elasticsearch._types.Script.of(sb -> {
 			sb.lang(scriptData.language())
-					.params(params);
-			if (scriptData.type() == ScriptType.INLINE) {
-				sb.source(scriptData.script());
-			} else if (scriptData.type() == ScriptType.STORED) {
-				sb.id(scriptData.script());
+					.params(params)
+					.id(scriptData.scriptName());
+			if (scriptData.script() != null) {
+				sb.source(s -> s.scriptString(scriptData.script()));
 			}
 			return sb;
 		});
@@ -926,9 +922,13 @@ class RequestConverter extends AbstractQueryProcessor {
 
 		ReindexRequest.Script script = reindexRequest.getScript();
 		if (script != null) {
-			builder.script(sb -> sb
-					.lang(script.getLang())
-					.source(script.getSource()));
+			builder.script(sb -> {
+				if (script.getSource() != null) {
+					sb.source(s -> s.scriptString(script.getSource()));
+				}
+				sb.lang(script.getLang());
+				return sb;
+			});
 		}
 
 		builder.timeout(time(reindexRequest.getTimeout())) //
@@ -1085,27 +1085,25 @@ class RequestConverter extends AbstractQueryProcessor {
 
 				uqb.script(sb -> {
 					sb.lang(query.getLang()).params(params);
-
-					if (query.getScriptType() == ScriptType.INLINE) {
-						sb.source(query.getScript()); //
-					} else if (query.getScriptType() == ScriptType.STORED) {
-						sb.id(query.getScript());
+					if (query.getScript() != null) {
+						sb.source(s -> s.scriptString(query.getScript()));
 					}
+					sb.id(query.getId());
+
 					return sb;
 				});
 			}
 
-			uqb //
-					.doc(query.getDocument()) //
-					.upsert(query.getUpsert()) //
-					.routing(query.getRouting() != null ? query.getRouting() : routing) //
-					.scriptedUpsert(query.getScriptedUpsert()) //
-					.docAsUpsert(query.getDocAsUpsert()) //
-					.ifSeqNo(query.getIfSeqNo() != null ? Long.valueOf(query.getIfSeqNo()) : null) //
-					.ifPrimaryTerm(query.getIfPrimaryTerm() != null ? Long.valueOf(query.getIfPrimaryTerm()) : null) //
-					.refresh(query.getRefreshPolicy() != null ? refresh(query.getRefreshPolicy()) : refresh(refreshPolicy)) //
-					.retryOnConflict(query.getRetryOnConflict()) //
-			;
+			uqb
+					.doc(query.getDocument())
+					.upsert(query.getUpsert())
+					.routing(query.getRouting() != null ? query.getRouting() : routing)
+					.scriptedUpsert(query.getScriptedUpsert())
+					.docAsUpsert(query.getDocAsUpsert())
+					.ifSeqNo(query.getIfSeqNo())
+					.ifPrimaryTerm(query.getIfPrimaryTerm())
+					.refresh(query.getRefreshPolicy() != null ? refresh(query.getRefreshPolicy()) : refresh(refreshPolicy))
+					.retryOnConflict(query.getRetryOnConflict());
 
 			if (query.getFetchSource() != null) {
 				uqb.source(sc -> sc.fetch(query.getFetchSource()));
@@ -1253,11 +1251,11 @@ class RequestConverter extends AbstractQueryProcessor {
 				mtrb.searchTemplates(stb -> stb
 						.header(msearchHeaderBuilder(query, param.index(), routing))
 						.body(bb -> {
-							bb //
-									.explain(query.getExplain()) //
-									.id(query.getId()) //
-									.source(query.getSource()) //
-							;
+							bb.explain(query.getExplain()) //
+									.id(query.getId()); //
+							if (query.getSource() != null) {
+								bb.source(s -> s.scriptString(query.getSource()));
+							}
 
 							if (!CollectionUtils.isEmpty(query.getParams())) {
 								Map<String, JsonData> params = getTemplateParams(query.getParams().entrySet());
@@ -1293,11 +1291,8 @@ class RequestConverter extends AbstractQueryProcessor {
 									.timeout(timeStringMs(query.getTimeout())) //
 							;
 
-							if (query.getPageable().isPaged()) {
-								bb //
-										.from((int) query.getPageable().getOffset()) //
-										.size(query.getPageable().getPageSize());
-							}
+							bb.from((int) (query.getPageable().isPaged() ? query.getPageable().getOffset() : 0))
+									.size(query.getRequestSize());
 
 							if (!isEmpty(query.getFields())) {
 								bb.fields(fb -> {
@@ -1310,10 +1305,6 @@ class RequestConverter extends AbstractQueryProcessor {
 								bb.storedFields(query.getStoredFields());
 							}
 
-							if (query.isLimiting()) {
-								bb.size(query.getMaxResults());
-							}
-
 							if (query.getMinScore() > 0) {
 								bb.minScore((double) query.getMinScore());
 							}
@@ -1348,7 +1339,9 @@ class RequestConverter extends AbstractQueryProcessor {
 
 										if (script != null) {
 											rfb.script(s -> {
-												s.source(script);
+												if (script != null) {
+													s.source(so -> so.scriptString(script));
+												}
 
 												if (runtimeField.getParams() != null) {
 													s.params(TypeUtils.paramsMap(runtimeField.getParams()));
@@ -1365,9 +1358,14 @@ class RequestConverter extends AbstractQueryProcessor {
 							}
 
 							if (!isEmpty(query.getIndicesBoost())) {
-								bb.indicesBoost(query.getIndicesBoost().stream()
-										.map(indexBoost -> Map.of(indexBoost.getIndexName(), (double) indexBoost.getBoost()))
-										.collect(Collectors.toList()));
+								Stream<NamedValue<Double>> namedValueStream = query.getIndicesBoost().stream()
+										.map(indexBoost -> {
+											var namedValue = new NamedValue(indexBoost.getIndexName(),
+													Float.valueOf(indexBoost.getBoost()).doubleValue());
+											return namedValue;
+										});
+								List<NamedValue<Double>> namedValueList = namedValueStream.collect(Collectors.toList());
+								bb.indicesBoost(namedValueList);
 							}
 
 							query.getScriptedFields().forEach(scriptedField -> bb.scriptFields(scriptedField.getFieldName(),
@@ -1466,13 +1464,8 @@ class RequestConverter extends AbstractQueryProcessor {
 			builder.seqNoPrimaryTerm(true);
 		}
 
-		if (query.getPageable().isPaged()) {
-			builder //
-					.from((int) query.getPageable().getOffset()) //
-					.size(query.getPageable().getPageSize());
-		} else {
-			builder.from(0).size(INDEX_MAX_RESULT_WINDOW);
-		}
+		builder.from((int) (query.getPageable().isPaged() ? query.getPageable().getOffset() : 0))
+				.size(query.getRequestSize());
 
 		if (!isEmpty(query.getFields())) {
 			var fieldAndFormats = query.getFields().stream().map(field -> FieldAndFormat.of(b -> b.field(field))).toList();
@@ -1487,10 +1480,6 @@ class RequestConverter extends AbstractQueryProcessor {
 			addIndicesOptions(builder, query.getIndicesOptions());
 		}
 
-		if (query.isLimiting()) {
-			builder.size(query.getMaxResults());
-		}
-
 		if (query.getMinScore() > 0) {
 			builder.minScore((double) query.getMinScore());
 		}
@@ -1548,7 +1537,9 @@ class RequestConverter extends AbstractQueryProcessor {
 						String script = runtimeField.getScript();
 						if (script != null) {
 							rfb.script(s -> {
-								s.source(script);
+								if (script != null) {
+									s.source(so -> so.scriptString(script));
+								}
 
 								if (runtimeField.getParams() != null) {
 									s.params(TypeUtils.paramsMap(runtimeField.getParams()));
@@ -1576,9 +1567,14 @@ class RequestConverter extends AbstractQueryProcessor {
 		}
 
 		if (!isEmpty(query.getIndicesBoost())) {
-			builder.indicesBoost(query.getIndicesBoost().stream()
-					.map(indexBoost -> Map.of(indexBoost.getIndexName(), (double) indexBoost.getBoost()))
-					.collect(Collectors.toList()));
+			Stream<NamedValue<Double>> namedValueStream = query.getIndicesBoost().stream()
+					.map(indexBoost -> {
+						var namedValue = new NamedValue(indexBoost.getIndexName(),
+								Float.valueOf(indexBoost.getBoost()).doubleValue());
+						return namedValue;
+					});
+			List<NamedValue<Double>> namedValueList = namedValueStream.collect(Collectors.toList());
+			builder.indicesBoost(namedValueList);
 		}
 
 		if (!isEmpty(query.getDocValueFields())) {
@@ -1640,7 +1636,7 @@ class RequestConverter extends AbstractQueryProcessor {
 		builder.highlight(highlight);
 	}
 
-	private void addHighlight(Query query, MultisearchBody.Builder builder) {
+	private void addHighlight(Query query, SearchRequestBody.Builder builder) {
 
 		Highlight highlight = query.getHighlightQuery()
 				.map(highlightQuery -> new HighlightQueryBuilder(elasticsearchConverter.getMappingContext(), this)
@@ -1720,7 +1716,7 @@ class RequestConverter extends AbstractQueryProcessor {
 	}
 
 	@Nullable
-	private NestedSortValue getNestedSort(@Nullable Order.Nested nested,
+	private NestedSortValue getNestedSort(Order.@Nullable Nested nested,
 			@Nullable ElasticsearchPersistentEntity<?> persistentEntity) {
 		return (nested == null || persistentEntity == null) ? null
 				: NestedSortValue.of(b -> b //
@@ -1764,7 +1760,7 @@ class RequestConverter extends AbstractQueryProcessor {
 	}
 
 	@SuppressWarnings("DuplicatedCode")
-	private void prepareNativeSearch(NativeQuery query, MultisearchBody.Builder builder) {
+	private void prepareNativeSearch(NativeQuery query, SearchRequestBody.Builder builder) {
 
 		builder //
 				.suggest(query.getSuggester()) //
@@ -1784,8 +1780,7 @@ class RequestConverter extends AbstractQueryProcessor {
 		}
 	}
 
-	@Nullable
-	co.elastic.clients.elasticsearch._types.query_dsl.Query getQuery(@Nullable Query query,
+	co.elastic.clients.elasticsearch._types.query_dsl.@Nullable Query getQuery(@Nullable Query query,
 			@Nullable Class<?> clazz) {
 		return getEsQuery(query, (q) -> elasticsearchConverter.updateQuery(q, clazz));
 	}
@@ -1884,10 +1879,11 @@ class RequestConverter extends AbstractQueryProcessor {
 					.id(query.getId()) //
 					.index(Arrays.asList(index.getIndexNames())) //
 					.preference(query.getPreference()) //
-					.searchType(searchType(query.getSearchType())) //
-					.source(query.getSource()) //
-			;
+					.searchType(searchType(query.getSearchType())); //
 
+			if (query.getSource() != null) {
+				builder.source(so -> so.scriptString(query.getSource()));
+			}
 			if (query.getRoute() != null) {
 				builder.routing(query.getRoute());
 			} else if (StringUtils.hasText(routing)) {
@@ -1930,7 +1926,7 @@ class RequestConverter extends AbstractQueryProcessor {
 				.id(script.id()) //
 				.script(sb -> sb //
 						.lang(script.language()) //
-						.source(script.source())));
+						.source(s -> s.scriptString(script.source()))));
 	}
 
 	public GetScriptRequest scriptGet(String name) {

src/main/java/org/springframework/data/elasticsearch/client/elc/ResponseConverter.java

@@ -48,6 +48,7 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.ElasticsearchErrorCause;
 import org.springframework.data.elasticsearch.core.IndexInformation;
 import org.springframework.data.elasticsearch.core.MultiGetItem;
@@ -65,7 +66,6 @@ import org.springframework.data.elasticsearch.core.reindex.ReindexResponse;
 import org.springframework.data.elasticsearch.core.script.Script;
 import org.springframework.data.elasticsearch.core.sql.SqlResponse;
 import org.springframework.data.elasticsearch.support.DefaultStringObjectMap;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -92,7 +92,7 @@ class ResponseConverter {
 		return ClusterHealth.builder() //
 				.withActivePrimaryShards(healthResponse.activePrimaryShards()) //
 				.withActiveShards(healthResponse.activeShards()) //
-				.withActiveShardsPercent(Double.parseDouble(healthResponse.activeShardsPercentAsNumber()))//
+				.withActiveShardsPercent(healthResponse.activeShardsPercentAsNumber())//
 				.withClusterName(healthResponse.clusterName()) //
 				.withDelayedUnassignedShards(healthResponse.delayedUnassignedShards()) //
 				.withInitializingShards(healthResponse.initializingShards()) //
@@ -191,7 +191,7 @@ class ResponseConverter {
 		Assert.notNull(getMappingResponse, "getMappingResponse must not be null");
 		Assert.notNull(indexCoordinates, "indexCoordinates must not be null");
 
-		Map<String, IndexMappingRecord> mappings = getMappingResponse.result();
+		Map<String, IndexMappingRecord> mappings = getMappingResponse.mappings();
 
 		if (mappings == null || mappings.isEmpty()) {
 			return Document.create();
@@ -219,7 +219,7 @@ class ResponseConverter {
 
 		List<IndexInformation> indexInformationList = new ArrayList<>();
 
-		getIndexResponse.result().forEach((indexName, indexState) -> {
+		getIndexResponse.indices().forEach((indexName, indexState) -> {
 			Settings settings = indexState.settings() != null ? Settings.parse(toJson(indexState.settings(), jsonpMapper))
 					: new Settings();
 			Document mappings = indexState.mappings() != null ? Document.parse(toJson(indexState.mappings(), jsonpMapper))
@@ -239,7 +239,7 @@ class ResponseConverter {
 		Assert.notNull(getAliasResponse, "getAliasResponse must not be null");
 
 		Map<String, Set<AliasData>> aliasDataMap = new HashMap<>();
-		getAliasResponse.result().forEach((indexName, alias) -> {
+		getAliasResponse.aliases().forEach((indexName, alias) -> {
 			Set<AliasData> aliasDataSet = new HashSet<>();
 			alias.aliases()
 					.forEach((aliasName, aliasDefinition) -> aliasDataSet.add(indicesGetAliasData(aliasName, aliasDefinition)));
@@ -400,7 +400,6 @@ class ResponseConverter {
 	private ReindexResponse.Failure reindexResponseFailureOf(BulkIndexByScrollFailure failure) {
 		return ReindexResponse.Failure.builder() //
 				.withIndex(failure.index()) //
-				.withType(failure.type()) //
 				.withId(failure.id()) //
 				.withStatus(failure.status())//
 				.withErrorCause(toErrorCause(failure.cause())) //
@@ -411,14 +410,12 @@ class ResponseConverter {
 	private ByQueryResponse.Failure byQueryResponseFailureOf(BulkIndexByScrollFailure failure) {
 		return ByQueryResponse.Failure.builder() //
 				.withIndex(failure.index()) //
-				.withType(failure.type()) //
 				.withId(failure.id()) //
 				.withStatus(failure.status())//
 				.withErrorCause(toErrorCause(failure.cause())).build();
 	}
 
-	@Nullable
-	public static MultiGetItem.Failure getFailure(MultiGetResponseItem<EntityAsMap> itemResponse) {
+	public static MultiGetItem.@Nullable Failure getFailure(MultiGetResponseItem<EntityAsMap> itemResponse) {
 
 		MultiGetError responseFailure = itemResponse.isFailure() ? itemResponse.failure() : null;
 
@@ -500,6 +497,10 @@ class ResponseConverter {
 			builder.withDeleted(response.deleted());
 		}
 
+		if(response.updated() != null) {
+			builder.withUpdated(response.updated());
+		}
+
 		if (response.batches() != null) {
 			builder.withBatches(Math.toIntExact(response.batches()));
 		}
@@ -534,7 +535,7 @@ class ResponseConverter {
 				? Script.builder() //
 						.withId(response.id()) //
 						.withLanguage(response.script().lang()) //
-						.withSource(response.script().source()).build() //
+						.withSource(response.script().source().scriptString()).build() //
 				: null;
 	}
 	// endregion

src/main/java/org/springframework/data/elasticsearch/client/elc/SearchDocumentResponseBuilder.java

@@ -39,6 +39,7 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.SearchShardStatistics;
 import org.springframework.data.elasticsearch.core.TotalHitsRelation;
 import org.springframework.data.elasticsearch.core.document.SearchDocument;
@@ -48,7 +49,6 @@ import org.springframework.data.elasticsearch.core.suggest.response.PhraseSugges
 import org.springframework.data.elasticsearch.core.suggest.response.Suggest;
 import org.springframework.data.elasticsearch.core.suggest.response.TermSuggestion;
 import org.springframework.data.elasticsearch.support.ScoreDoc;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 
@@ -133,7 +133,8 @@ class SearchDocumentResponseBuilder {
 	 * @return the {@link SearchDocumentResponse}
 	 */
 	public static <T> SearchDocumentResponse from(HitsMetadata<?> hitsMetadata, @Nullable ShardStatistics shards,
-			@Nullable String scrollId, @Nullable String pointInTimeId, long executionDurationInMillis, @Nullable Map<String, Aggregate> aggregations,
+			@Nullable String scrollId, @Nullable String pointInTimeId, long executionDurationInMillis,
+			@Nullable Map<String, Aggregate> aggregations,
 			Map<String, List<Suggestion<EntityAsMap>>> suggestES, SearchDocumentResponse.EntityCreator<T> entityCreator,
 			JsonpMapper jsonpMapper) {
 
@@ -171,7 +172,8 @@ class SearchDocumentResponseBuilder {
 
 		SearchShardStatistics shardStatistics = shards != null ? shardsFrom(shards) : null;
 
-		return new SearchDocumentResponse(totalHits, totalHitsRelation, maxScore, executionDuration, scrollId, pointInTimeId, searchDocuments,
+		return new SearchDocumentResponse(totalHits, totalHitsRelation, maxScore, executionDuration, scrollId,
+				pointInTimeId, searchDocuments,
 				aggregationsContainer, suggest, shardStatistics);
 	}
 

src/main/java/org/springframework/data/elasticsearch/client/elc/TypeUtils.java

@@ -38,6 +38,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.elasticsearch.core.RefreshPolicy;
 import org.springframework.data.elasticsearch.core.document.Document;
@@ -52,7 +53,6 @@ import org.springframework.data.elasticsearch.core.query.UpdateResponse;
 import org.springframework.data.elasticsearch.core.query.types.ConflictsType;
 import org.springframework.data.elasticsearch.core.query.types.OperatorType;
 import org.springframework.data.elasticsearch.core.reindex.ReindexRequest;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -220,7 +220,7 @@ final class TypeUtils {
 	}
 
 	@Nullable
-	static SortOrder sortOrder(@Nullable Sort.Direction direction) {
+	static SortOrder sortOrder(Sort.@Nullable Direction direction) {
 
 		if (direction == null) {
 			return null;
@@ -301,7 +301,7 @@ final class TypeUtils {
 	}
 
 	@Nullable
-	static OpType opType(@Nullable IndexQuery.OpType opType) {
+	static OpType opType(IndexQuery.@Nullable OpType opType) {
 
 		if (opType != null) {
 			return switch (opType) {
@@ -325,8 +325,7 @@ final class TypeUtils {
 		};
 	}
 
-	@Nullable
-	static UpdateResponse.Result result(@Nullable Result result) {
+	static UpdateResponse.@Nullable Result result(@Nullable Result result) {
 
 		if (result == null) {
 			return null;
@@ -343,7 +342,7 @@ final class TypeUtils {
 	}
 
 	@Nullable
-	static ScoreMode scoreMode(@Nullable RescorerQuery.ScoreMode scoreMode) {
+	static ScoreMode scoreMode(RescorerQuery.@Nullable ScoreMode scoreMode) {
 
 		if (scoreMode == null) {
 			return null;
@@ -361,7 +360,7 @@ final class TypeUtils {
 	}
 
 	@Nullable
-	static SearchType searchType(@Nullable Query.SearchType searchType) {
+	static SearchType searchType(Query.@Nullable SearchType searchType) {
 
 		if (searchType == null) {
 			return null;
@@ -418,7 +417,7 @@ final class TypeUtils {
 
 	@Nullable
 	static VersionType versionType(
-			@Nullable org.springframework.data.elasticsearch.annotations.Document.VersionType versionType) {
+			org.springframework.data.elasticsearch.annotations.Document.@Nullable VersionType versionType) {
 
 		if (versionType != null) {
 			return switch (versionType) {
@@ -536,7 +535,7 @@ final class TypeUtils {
 	 * @param scoreMode spring-data-elasticsearch {@literal scoreMode}.
 	 * @return an Elasticsearch {@literal scoreMode}.
 	 */
-	static ChildScoreMode scoreMode(@Nullable HasChildQuery.ScoreMode scoreMode) {
+	static ChildScoreMode scoreMode(HasChildQuery.@Nullable ScoreMode scoreMode) {
 		if (scoreMode == null) {
 			return ChildScoreMode.None;
 		}

src/main/java/org/springframework/data/elasticsearch/client/elc/aot/ElasticsearchClientRuntimeHints.java

@@ -19,11 +19,11 @@ import co.elastic.clients.elasticsearch._types.mapping.RuntimeFieldType;
 import co.elastic.clients.elasticsearch._types.mapping.TypeMapping;
 import co.elastic.clients.elasticsearch.indices.IndexSettings;
 import co.elastic.clients.elasticsearch.indices.PutMappingRequest;
-import org.springframework.aot.hint.MemberCategory;
+
+import org.jspecify.annotations.Nullable;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
 import org.springframework.aot.hint.TypeReference;
-import org.springframework.lang.Nullable;
 
 /**
  * runtime hints for the Elasticsearch client libraries, as these do not provide any of their own.

src/main/java/org/springframework/data/elasticsearch/client/elc/aot/package-info.java

@@ -1,3 +1,2 @@
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.client.elc.aot;

src/main/java/org/springframework/data/elasticsearch/client/elc/package-info.java

@@ -18,6 +18,5 @@
  * This package contains classes that use the new Elasticsearch client library (co.elastic.clients:elasticsearch-java)
  * to access Elasticsearch.
  */
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.client.elc;

src/main/java/org/springframework/data/elasticsearch/client/elc/rest5_client/Rest5Clients.java

@@ -0,0 +1,274 @@
+package org.springframework.data.elasticsearch.client.elc.rest5_client;
+
+import co.elastic.clients.transport.TransportOptions;
+import co.elastic.clients.transport.TransportUtils;
+import co.elastic.clients.transport.rest5_client.Rest5ClientOptions;
+import co.elastic.clients.transport.rest5_client.low_level.RequestOptions;
+import co.elastic.clients.transport.rest5_client.low_level.Rest5Client;
+import co.elastic.clients.transport.rest5_client.low_level.Rest5ClientBuilder;
+
+import java.net.InetSocketAddress;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.security.NoSuchAlgorithmException;
+import java.time.Duration;
+import java.util.List;
+import java.util.Locale;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Function;
+
+import javax.net.ssl.SSLContext;
+
+import org.apache.hc.client5.http.config.ConnectionConfig;
+import org.apache.hc.client5.http.config.RequestConfig;
+import org.apache.hc.client5.http.impl.DefaultAuthenticationStrategy;
+import org.apache.hc.client5.http.impl.async.CloseableHttpAsyncClient;
+import org.apache.hc.client5.http.impl.async.HttpAsyncClientBuilder;
+import org.apache.hc.client5.http.impl.nio.PoolingAsyncClientConnectionManager;
+import org.apache.hc.client5.http.impl.nio.PoolingAsyncClientConnectionManagerBuilder;
+import org.apache.hc.client5.http.impl.routing.DefaultProxyRoutePlanner;
+import org.apache.hc.core5.http.Header;
+import org.apache.hc.core5.http.HttpHost;
+import org.apache.hc.core5.http.message.BasicHeader;
+import org.apache.hc.core5.http.nio.ssl.BasicClientTlsStrategy;
+import org.apache.hc.core5.util.Timeout;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
+import org.springframework.data.elasticsearch.client.ClientConfiguration;
+import org.springframework.data.elasticsearch.support.HttpHeaders;
+import org.springframework.data.elasticsearch.support.VersionInfo;
+import org.springframework.util.Assert;
+
+/**
+ * Utility class containing the functions to create the Elasticsearch Rest5Client used from Elasticsearch 9 on.
+ *
+ * @since 6.0
+ */
+public final class Rest5Clients {
+
+	// values copied from Rest5ClientBuilder
+	public static final int DEFAULT_CONNECT_TIMEOUT_MILLIS = 1000;
+	public static final int DEFAULT_SOCKET_TIMEOUT_MILLIS = 30000;
+	public static final int DEFAULT_RESPONSE_TIMEOUT_MILLIS = 0; // meaning infinite
+	public static final int DEFAULT_MAX_CONN_PER_ROUTE = 10;
+	public static final int DEFAULT_MAX_CONN_TOTAL = 30;
+
+	private Rest5Clients() {}
+
+	/**
+	 * Creates a low level {@link Rest5Client} for the given configuration.
+	 *
+	 * @param clientConfiguration must not be {@literal null}
+	 * @return the {@link Rest5Client}
+	 */
+	public static Rest5Client getRest5Client(ClientConfiguration clientConfiguration) {
+		return getRest5ClientBuilder(clientConfiguration).build();
+	}
+
+	private static Rest5ClientBuilder getRest5ClientBuilder(ClientConfiguration clientConfiguration) {
+
+		HttpHost[] httpHosts = getHttpHosts(clientConfiguration);
+		Rest5ClientBuilder builder = Rest5Client.builder(httpHosts);
+
+		if (clientConfiguration.getPathPrefix() != null) {
+			builder.setPathPrefix(clientConfiguration.getPathPrefix());
+		}
+
+		HttpHeaders headers = clientConfiguration.getDefaultHeaders();
+
+		if (!headers.isEmpty()) {
+			builder.setDefaultHeaders(toHeaderArray(headers));
+		}
+
+		// we need to provide our own HttpClient, as the Rest5ClientBuilder
+		// does not provide a callback for configuration the http client as the old RestClientBuilder.
+		var httpClient = createHttpClient(clientConfiguration);
+		builder.setHttpClient(httpClient);
+
+		for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurationCallback : clientConfiguration
+				.getClientConfigurers()) {
+			if (clientConfigurationCallback instanceof ElasticsearchRest5ClientConfigurationCallback configurationCallback) {
+				builder = configurationCallback.configure(builder);
+			}
+		}
+
+		return builder;
+	}
+
+	private static HttpHost @NonNull [] getHttpHosts(ClientConfiguration clientConfiguration) {
+		List<InetSocketAddress> hosts = clientConfiguration.getEndpoints();
+		boolean useSsl = clientConfiguration.useSsl();
+		return hosts.stream()
+				.map(it -> (useSsl ? "https" : "http") + "://" + it.getHostString() + ':' + it.getPort())
+				.map(URI::create)
+				.map(HttpHost::create)
+				.toArray(HttpHost[]::new);
+	}
+
+	private static Header[] toHeaderArray(HttpHeaders headers) {
+		return headers.entrySet().stream() //
+				.flatMap(entry -> entry.getValue().stream() //
+						.map(value -> new BasicHeader(entry.getKey(), value))) //
+				.toList().toArray(new Header[0]);
+	}
+
+	// the basic logic to create the http client is copied from the Rest5ClientBuilder class, this is taken from the
+	// Elasticsearch code, as there is no public usable instance in that
+	private static CloseableHttpAsyncClient createHttpClient(ClientConfiguration clientConfiguration) {
+
+		var requestConfigBuilder = RequestConfig.custom();
+		var connectionConfigBuilder = ConnectionConfig.custom();
+
+		Duration connectTimeout = clientConfiguration.getConnectTimeout();
+
+		if (!connectTimeout.isNegative()) {
+			connectionConfigBuilder.setConnectTimeout(
+					Timeout.of(Math.toIntExact(connectTimeout.toMillis()), TimeUnit.MILLISECONDS));
+		}
+
+		Duration socketTimeout = clientConfiguration.getSocketTimeout();
+
+		if (!socketTimeout.isNegative()) {
+			var soTimeout = Timeout.of(Math.toIntExact(socketTimeout.toMillis()), TimeUnit.MILLISECONDS);
+			connectionConfigBuilder.setSocketTimeout(soTimeout);
+			requestConfigBuilder.setConnectionRequestTimeout(soTimeout);
+		} else {
+			connectionConfigBuilder.setSocketTimeout(Timeout.of(DEFAULT_SOCKET_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS));
+			requestConfigBuilder
+					.setConnectionRequestTimeout(Timeout.of(DEFAULT_RESPONSE_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS));
+		}
+
+		try {
+			SSLContext sslContext = clientConfiguration.getCaFingerprint().isPresent()
+					? TransportUtils.sslContextFromCaFingerprint(clientConfiguration.getCaFingerprint().get())
+					: (clientConfiguration.getSslContext().isPresent()
+							? clientConfiguration.getSslContext().get()
+							: SSLContext.getDefault());
+
+			ConnectionConfig connectionConfig = connectionConfigBuilder.build();
+
+			PoolingAsyncClientConnectionManager defaultConnectionManager = PoolingAsyncClientConnectionManagerBuilder.create()
+					.setDefaultConnectionConfig(connectionConfig)
+					.setMaxConnPerRoute(DEFAULT_MAX_CONN_PER_ROUTE)
+					.setMaxConnTotal(DEFAULT_MAX_CONN_TOTAL)
+					.setTlsStrategy(new BasicClientTlsStrategy(sslContext))
+					.build();
+
+			var requestConfig = requestConfigBuilder.build();
+
+            var immutableRefToHttpClientBuilder = new Object() {
+                HttpAsyncClientBuilder httpClientBuilder = HttpAsyncClientBuilder.create()
+                        .setDefaultRequestConfig(requestConfig)
+                        .setConnectionManager(defaultConnectionManager)
+                        .setUserAgent(VersionInfo.clientVersions())
+                        .setTargetAuthenticationStrategy(new DefaultAuthenticationStrategy())
+                        .setThreadFactory(new RestClientThreadFactory());
+            };
+
+			clientConfiguration.getProxy().ifPresent(proxy -> {
+				try {
+					var proxyRoutePlanner = new DefaultProxyRoutePlanner(HttpHost.create(proxy));
+					immutableRefToHttpClientBuilder.httpClientBuilder.setRoutePlanner(proxyRoutePlanner);
+				} catch (URISyntaxException e) {
+					throw new RuntimeException(e);
+				}
+			});
+
+			immutableRefToHttpClientBuilder.httpClientBuilder.addRequestInterceptorFirst((request, entity, context) -> {
+				clientConfiguration.getHeadersSupplier().get().forEach((header, values) -> {
+					// The accept and content-type headers are already put on the request, despite this being the first
+					// interceptor.
+					if ("Accept".equalsIgnoreCase(header) || " Content-Type".equalsIgnoreCase(header)) {
+						request.removeHeaders(header);
+					}
+					values.forEach(value -> request.addHeader(header, value));
+				});
+			});
+
+			for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurer : clientConfiguration
+					.getClientConfigurers()) {
+				if (clientConfigurer instanceof ElasticsearchHttpClientConfigurationCallback httpClientConfigurer) {
+					immutableRefToHttpClientBuilder.httpClientBuilder = httpClientConfigurer.configure(immutableRefToHttpClientBuilder.httpClientBuilder);
+				}
+			}
+
+			return immutableRefToHttpClientBuilder.httpClientBuilder.build();
+		} catch (NoSuchAlgorithmException e) {
+			throw new IllegalStateException("could not create the default ssl context", e);
+		}
+	}
+
+	/*
+	 * Copied from the Elasticsearch code as this class is not public there.
+	 */
+	private static class RestClientThreadFactory implements ThreadFactory {
+		private static final AtomicLong CLIENT_THREAD_POOL_ID_GENERATOR = new AtomicLong();
+		private final long clientThreadPoolId;
+		private final AtomicLong clientThreadId;
+
+		private RestClientThreadFactory() {
+			this.clientThreadPoolId = CLIENT_THREAD_POOL_ID_GENERATOR.getAndIncrement();
+			this.clientThreadId = new AtomicLong();
+		}
+
+		public Thread newThread(Runnable runnable) {
+			return new Thread(runnable, String.format(Locale.ROOT, "elasticsearch-rest-client-%d-thread-%d",
+					this.clientThreadPoolId, this.clientThreadId.incrementAndGet()));
+		}
+	}
+
+	/**
+	 * {@link org.springframework.data.elasticsearch.client.ClientConfiguration.ClientConfigurationCallback} to configure
+	 * the Elasticsearch Rest5Client's Http client with a {@link HttpAsyncClientBuilder}
+	 *
+	 * @since 6.0
+	 */
+	public interface ElasticsearchHttpClientConfigurationCallback
+			extends ClientConfiguration.ClientConfigurationCallback<HttpAsyncClientBuilder> {
+
+		static Rest5Clients.ElasticsearchHttpClientConfigurationCallback from(
+				Function<HttpAsyncClientBuilder, HttpAsyncClientBuilder> httpClientBuilderCallback) {
+
+			Assert.notNull(httpClientBuilderCallback, "httpClientBuilderCallback must not be null");
+
+			return httpClientBuilderCallback::apply;
+		}
+	}
+
+	/**
+	 * {@link ClientConfiguration.ClientConfigurationCallback} to configure the Rest5Client client with a
+	 * {@link Rest5ClientBuilder}
+	 *
+	 * @since 6.0
+	 */
+	public interface ElasticsearchRest5ClientConfigurationCallback
+			extends ClientConfiguration.ClientConfigurationCallback<Rest5ClientBuilder> {
+
+		static ElasticsearchRest5ClientConfigurationCallback from(
+				Function<Rest5ClientBuilder, Rest5ClientBuilder> rest5ClientBuilderCallback) {
+
+			Assert.notNull(rest5ClientBuilderCallback, "rest5ClientBuilderCallback must not be null");
+
+			return rest5ClientBuilderCallback::apply;
+		}
+	}
+
+	public static Rest5ClientOptions.Builder getRest5ClientOptionsBuilder(@Nullable TransportOptions transportOptions) {
+
+		if (transportOptions instanceof Rest5ClientOptions rest5ClientOptions) {
+			return rest5ClientOptions.toBuilder();
+		}
+
+		var builder = new Rest5ClientOptions.Builder(RequestOptions.DEFAULT.toBuilder());
+
+		if (transportOptions != null) {
+			transportOptions.headers().forEach(header -> builder.addHeader(header.getKey(), header.getValue()));
+			transportOptions.queryParameters().forEach(builder::setParameter);
+			builder.onWarnings(transportOptions.onWarnings());
+		}
+
+		return builder;
+	}
+}

src/main/java/org/springframework/data/elasticsearch/client/elc/rest5_client/package-info.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2025 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.
+ */
+
+/**
+ * This package contains related to the new (from Elasticsearch 9 on) Rest5Client. There are also classes copied over from Elasticsearch in order to have a Rest5ClientBuilder that allows to configure the http client.
+ */
+@org.jspecify.annotations.NullMarked
+package org.springframework.data.elasticsearch.client.elc.rest5_client;

src/main/java/org/springframework/data/elasticsearch/client/elc/rest_client/RestClients.java

@@ -0,0 +1,195 @@
+package org.springframework.data.elasticsearch.client.elc.rest_client;
+
+import co.elastic.clients.transport.TransportOptions;
+import co.elastic.clients.transport.TransportUtils;
+import co.elastic.clients.transport.rest_client.RestClientOptions;
+
+import java.net.InetSocketAddress;
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import org.apache.http.HttpHost;
+import org.apache.http.HttpRequest;
+import org.apache.http.HttpRequestInterceptor;
+import org.apache.http.client.config.RequestConfig;
+import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
+import org.apache.http.message.BasicHeader;
+import org.apache.http.protocol.HttpContext;
+import org.elasticsearch.client.RequestOptions;
+import org.elasticsearch.client.RestClient;
+import org.elasticsearch.client.RestClientBuilder;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
+import org.springframework.data.elasticsearch.client.ClientConfiguration;
+import org.springframework.data.elasticsearch.client.elc.ElasticsearchClients;
+import org.springframework.data.elasticsearch.support.HttpHeaders;
+import org.springframework.util.Assert;
+
+/**
+ * Utility class containing the functions to create the Elasticsearch RestClient used up to Elasticsearch 9.
+ *
+ * @since 6.0
+ * @deprecated since 6.0, use the new Rest5Client the code for that is in the package ../rest_client.
+ */
+@Deprecated(since = "6.0", forRemoval = true)
+public final class RestClients {
+
+	/**
+	 * Creates a low level {@link RestClient} for the given configuration.
+	 *
+	 * @param clientConfiguration must not be {@literal null}
+	 * @return the {@link RestClient}
+	 */
+	public static RestClient getRestClient(ClientConfiguration clientConfiguration) {
+		return getRestClientBuilder(clientConfiguration).build();
+	}
+
+	private static RestClientBuilder getRestClientBuilder(ClientConfiguration clientConfiguration) {
+		HttpHost[] httpHosts = getHttpHosts(clientConfiguration);
+		RestClientBuilder builder = RestClient.builder(httpHosts);
+
+		if (clientConfiguration.getPathPrefix() != null) {
+			builder.setPathPrefix(clientConfiguration.getPathPrefix());
+		}
+
+		HttpHeaders headers = clientConfiguration.getDefaultHeaders();
+
+		if (!headers.isEmpty()) {
+			builder.setDefaultHeaders(toHeaderArray(headers));
+		}
+
+		builder.setHttpClientConfigCallback(clientBuilder -> {
+			if (clientConfiguration.getCaFingerprint().isPresent()) {
+				clientBuilder
+						.setSSLContext(TransportUtils.sslContextFromCaFingerprint(clientConfiguration.getCaFingerprint().get()));
+			}
+			clientConfiguration.getSslContext().ifPresent(clientBuilder::setSSLContext);
+			clientConfiguration.getHostNameVerifier().ifPresent(clientBuilder::setSSLHostnameVerifier);
+			clientBuilder.addInterceptorLast(new CustomHeaderInjector(clientConfiguration.getHeadersSupplier()));
+
+			RequestConfig.Builder requestConfigBuilder = RequestConfig.custom();
+			Duration connectTimeout = clientConfiguration.getConnectTimeout();
+
+			if (!connectTimeout.isNegative()) {
+				requestConfigBuilder.setConnectTimeout(Math.toIntExact(connectTimeout.toMillis()));
+			}
+
+			Duration socketTimeout = clientConfiguration.getSocketTimeout();
+
+			if (!socketTimeout.isNegative()) {
+				requestConfigBuilder.setSocketTimeout(Math.toIntExact(socketTimeout.toMillis()));
+				requestConfigBuilder.setConnectionRequestTimeout(Math.toIntExact(socketTimeout.toMillis()));
+			}
+
+			clientBuilder.setDefaultRequestConfig(requestConfigBuilder.build());
+
+			clientConfiguration.getProxy().map(HttpHost::create).ifPresent(clientBuilder::setProxy);
+
+			for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurer : clientConfiguration
+					.getClientConfigurers()) {
+				if (clientConfigurer instanceof RestClients.ElasticsearchHttpClientConfigurationCallback restClientConfigurationCallback) {
+					clientBuilder = restClientConfigurationCallback.configure(clientBuilder);
+				}
+			}
+
+			return clientBuilder;
+		});
+
+		for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurationCallback : clientConfiguration
+				.getClientConfigurers()) {
+			if (clientConfigurationCallback instanceof ElasticsearchRestClientConfigurationCallback configurationCallback) {
+				builder = configurationCallback.configure(builder);
+			}
+		}
+		return builder;
+	}
+
+	private static HttpHost @NonNull [] getHttpHosts(ClientConfiguration clientConfiguration) {
+		List<InetSocketAddress> hosts = clientConfiguration.getEndpoints();
+		boolean useSsl = clientConfiguration.useSsl();
+		return hosts.stream()
+				.map(it -> (useSsl ? "https" : "http") + "://" + it.getHostString() + ':' + it.getPort())
+				.map(HttpHost::create).toArray(HttpHost[]::new);
+	}
+
+	private static org.apache.http.Header[] toHeaderArray(HttpHeaders headers) {
+		return headers.entrySet().stream() //
+				.flatMap(entry -> entry.getValue().stream() //
+						.map(value -> new BasicHeader(entry.getKey(), value))) //
+				.toArray(org.apache.http.Header[]::new);
+	}
+
+	/**
+	 * Interceptor to inject custom supplied headers.
+	 *
+	 * @since 4.4
+	 */
+	record CustomHeaderInjector(Supplier<HttpHeaders> headersSupplier) implements HttpRequestInterceptor {
+
+		@Override
+		public void process(HttpRequest request, HttpContext context) {
+			HttpHeaders httpHeaders = headersSupplier.get();
+
+			if (httpHeaders != null && !httpHeaders.isEmpty()) {
+				Arrays.stream(toHeaderArray(httpHeaders)).forEach(request::addHeader);
+			}
+		}
+	}
+
+	/**
+	 * {@link org.springframework.data.elasticsearch.client.ClientConfiguration.ClientConfigurationCallback} to configure
+	 * the Elasticsearch RestClient's Http client with a {@link HttpAsyncClientBuilder}
+	 *
+	 * @since 4.4
+	 */
+	public interface ElasticsearchHttpClientConfigurationCallback
+			extends ClientConfiguration.ClientConfigurationCallback<HttpAsyncClientBuilder> {
+
+		static RestClients.ElasticsearchHttpClientConfigurationCallback from(
+				Function<HttpAsyncClientBuilder, HttpAsyncClientBuilder> httpClientBuilderCallback) {
+
+			Assert.notNull(httpClientBuilderCallback, "httpClientBuilderCallback must not be null");
+
+			return httpClientBuilderCallback::apply;
+		}
+	}
+
+	/**
+	 * {@link org.springframework.data.elasticsearch.client.ClientConfiguration.ClientConfigurationCallback} to configure
+	 * the RestClient client with a {@link RestClientBuilder}
+	 *
+	 * @since 5.0
+	 */
+	public interface ElasticsearchRestClientConfigurationCallback
+			extends ClientConfiguration.ClientConfigurationCallback<RestClientBuilder> {
+
+		static ElasticsearchRestClientConfigurationCallback from(
+				Function<RestClientBuilder, RestClientBuilder> restClientBuilderCallback) {
+
+			Assert.notNull(restClientBuilderCallback, "restClientBuilderCallback must not be null");
+
+			return restClientBuilderCallback::apply;
+		}
+	}
+
+	public static RestClientOptions.Builder getRestClientOptionsBuilder(@Nullable TransportOptions transportOptions) {
+
+		if (transportOptions instanceof RestClientOptions restClientOptions) {
+			return restClientOptions.toBuilder();
+		}
+
+		var builder = new RestClientOptions.Builder(RequestOptions.DEFAULT.toBuilder());
+
+		if (transportOptions != null) {
+			transportOptions.headers().forEach(header -> builder.addHeader(header.getKey(), header.getValue()));
+			transportOptions.queryParameters().forEach(builder::setParameter);
+			builder.onWarnings(transportOptions.onWarnings());
+		}
+
+		return builder;
+	}
+
+}

src/main/java/org/springframework/data/elasticsearch/client/elc/rest_client/package-info.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021-2025 the original author or authors.
+ * Copyright 2022-2025 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.
@@ -13,15 +13,10 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.data.elasticsearch.core.query;
 
 /**
- * Define script types for update queries.
- *
- * @author Farid Faoudi
- * @since 4.2
+ * This package contains related to the old (up to Elasticsearch 9) RestClient.
  */
-
-public enum ScriptType {
-	INLINE, STORED
-}
+@Deprecated(since = "6.0", forRemoval=true)
+@org.jspecify.annotations.NullMarked
+package org.springframework.data.elasticsearch.client.elc.rest_client;

src/main/java/org/springframework/data/elasticsearch/client/package-info.java

@@ -1,3 +1,2 @@
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.client;

src/main/java/org/springframework/data/elasticsearch/client/util/ScrollState.java

@@ -19,7 +19,7 @@ import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.springframework.util.StringUtils;
 
 /**

src/main/java/org/springframework/data/elasticsearch/client/util/package-info.java

@@ -1,3 +1,2 @@
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.client.util;

src/main/java/org/springframework/data/elasticsearch/config/ElasticsearchAuditingBeanDefinitionParser.java

@@ -17,6 +17,7 @@ package org.springframework.data.elasticsearch.config;
 
 import static org.springframework.data.config.ParsingUtils.*;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
@@ -28,7 +29,6 @@ import org.springframework.data.auditing.config.IsNewAwareAuditingHandlerBeanDef
 import org.springframework.data.elasticsearch.core.event.AuditingEntityCallback;
 import org.springframework.data.elasticsearch.core.event.ReactiveAuditingEntityCallback;
 import org.springframework.data.elasticsearch.core.mapping.SimpleElasticsearchMappingContext;
-import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 import org.w3c.dom.Element;

src/main/java/org/springframework/data/elasticsearch/config/ElasticsearchConfigurationSupport.java

@@ -20,6 +20,7 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
@@ -34,7 +35,6 @@ import org.springframework.data.elasticsearch.core.convert.MappingElasticsearchC
 import org.springframework.data.elasticsearch.core.mapping.SimpleElasticsearchMappingContext;
 import org.springframework.data.mapping.model.FieldNamingStrategy;
 import org.springframework.data.mapping.model.PropertyNameFieldNamingStrategy;
-import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 

src/main/java/org/springframework/data/elasticsearch/config/package-info.java

@@ -1,3 +1,2 @@
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.config;

src/main/java/org/springframework/data/elasticsearch/core/AbstractElasticsearchTemplate.java

@@ -24,6 +24,7 @@ import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.beans.BeansException;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
@@ -57,7 +58,6 @@ import org.springframework.data.elasticsearch.support.VersionInfo;
 import org.springframework.data.mapping.callback.EntityCallbacks;
 import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.util.Streamable;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 

src/main/java/org/springframework/data/elasticsearch/core/AbstractReactiveElasticsearchTemplate.java

@@ -26,6 +26,7 @@ import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 import org.springframework.beans.BeansException;
@@ -56,7 +57,6 @@ import org.springframework.data.elasticsearch.core.script.Script;
 import org.springframework.data.elasticsearch.core.suggest.response.Suggest;
 import org.springframework.data.elasticsearch.support.VersionInfo;
 import org.springframework.data.mapping.callback.ReactiveEntityCallbacks;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -233,6 +233,7 @@ abstract public class AbstractReactiveElasticsearchTemplate
 					.subscribe(new Subscriber<>() {
 						@Nullable private Subscription subscription = null;
 						private final AtomicBoolean upstreamComplete = new AtomicBoolean(false);
+						private final AtomicBoolean onNextHasBeenCalled = new AtomicBoolean(false);
 
 						@Override
 						public void onSubscribe(Subscription subscription) {
@@ -242,6 +243,7 @@ abstract public class AbstractReactiveElasticsearchTemplate
 
 						@Override
 						public void onNext(List<T> entityList) {
+							onNextHasBeenCalled.set(true);
 							saveAll(entityList, index)
 									.map(sink::tryEmitNext)
 									.doOnComplete(() -> {
@@ -267,6 +269,10 @@ abstract public class AbstractReactiveElasticsearchTemplate
 						@Override
 						public void onComplete() {
 							upstreamComplete.set(true);
+							if (!onNextHasBeenCalled.get()) {
+								// this happens when an empty flux is saved
+								sink.tryEmitComplete();
+							}
 						}
 					});
 			return sink.asFlux();

src/main/java/org/springframework/data/elasticsearch/core/DocumentOperations.java

@@ -18,6 +18,7 @@ package org.springframework.data.elasticsearch.core;
 import java.util.Collection;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
 import org.springframework.data.elasticsearch.core.query.BulkOptions;
 import org.springframework.data.elasticsearch.core.query.ByQueryResponse;
@@ -28,7 +29,6 @@ import org.springframework.data.elasticsearch.core.query.UpdateQuery;
 import org.springframework.data.elasticsearch.core.query.UpdateResponse;
 import org.springframework.data.elasticsearch.core.reindex.ReindexRequest;
 import org.springframework.data.elasticsearch.core.reindex.ReindexResponse;
-import org.springframework.lang.Nullable;
 
 /**
  * The operations for the

src/main/java/org/springframework/data/elasticsearch/core/ElasticsearchOperations.java

@@ -15,13 +15,13 @@
  */
 package org.springframework.data.elasticsearch.core;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.cluster.ClusterOperations;
 import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
 import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
 import org.springframework.data.elasticsearch.core.routing.RoutingResolver;
 import org.springframework.data.elasticsearch.core.script.ScriptOperations;
 import org.springframework.data.elasticsearch.core.sql.SqlOperations;
-import org.springframework.lang.Nullable;
 
 /**
  * ElasticsearchOperations. Since 4.0 this interface only contains common helper functions, the other methods have been

src/main/java/org/springframework/data/elasticsearch/core/EntityOperations.java

@@ -17,6 +17,7 @@ package org.springframework.data.elasticsearch.core;
 
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
 import org.springframework.data.elasticsearch.core.join.JoinField;
@@ -29,7 +30,6 @@ import org.springframework.data.mapping.IdentifierAccessor;
 import org.springframework.data.mapping.PersistentPropertyAccessor;
 import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.mapping.model.ConvertingPropertyAccessor;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -123,7 +123,7 @@ public class EntityOperations {
 
 			// Only deal with text because ES generated Ids are strings!
 			if (indexedObjectInformation.id() != null && idProperty != null
-					// isReadable from the base class is false in case of records
+			// isReadable from the base class is false in case of records
 					&& (idProperty.isReadable() || idProperty.getOwner().getType().isRecord())
 					&& idProperty.getType().isAssignableFrom(String.class)) {
 				propertyAccessor.setProperty(idProperty, indexedObjectInformation.id());

src/main/java/org/springframework/data/elasticsearch/core/IndexInformation.java

@@ -18,10 +18,10 @@ package org.springframework.data.elasticsearch.core;
 
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.document.Document;
 import org.springframework.data.elasticsearch.core.index.AliasData;
 import org.springframework.data.elasticsearch.core.index.Settings;
-import org.springframework.lang.Nullable;
 
 /**
  * Immutable object that holds information(name, settings, mappings, aliases) about an Index

src/main/java/org/springframework/data/elasticsearch/core/IndexOperations.java

@@ -19,10 +19,10 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.document.Document;
 import org.springframework.data.elasticsearch.core.index.*;
 import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
-import org.springframework.lang.Nullable;
 
 /**
  * The operations for the

src/main/java/org/springframework/data/elasticsearch/core/IndexOperationsAdapter.java

@@ -22,10 +22,10 @@ import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.document.Document;
 import org.springframework.data.elasticsearch.core.index.*;
 import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/core/IndexedObjectInformation.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.data.elasticsearch.core;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Value class capturing information about a newly indexed document in Elasticsearch.

src/main/java/org/springframework/data/elasticsearch/core/MultiGetItem.java

@@ -15,8 +15,8 @@
  */
 package org.springframework.data.elasticsearch.core;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.ElasticsearchErrorCause;
-import org.springframework.lang.Nullable;
 
 /**
  * Response object for items returned from multiget requests, encapsulating the returned data and potential error

src/main/java/org/springframework/data/elasticsearch/core/ReactiveElasticsearchOperations.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.elasticsearch.core;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.cluster.ReactiveClusterOperations;
 import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
 import org.springframework.data.elasticsearch.core.mapping.ElasticsearchPersistentEntity;
@@ -22,7 +23,6 @@ import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
 import org.springframework.data.elasticsearch.core.routing.RoutingResolver;
 import org.springframework.data.elasticsearch.core.script.ReactiveScriptOperations;
 import org.springframework.data.elasticsearch.core.sql.ReactiveSqlOperations;
-import org.springframework.lang.Nullable;
 
 /**
  * Interface that specifies a basic set of Elasticsearch operations executed in a reactive way.

src/main/java/org/springframework/data/elasticsearch/core/ReactiveSearchHits.java

@@ -19,8 +19,8 @@ import reactor.core.publisher.Flux;
 
 import java.time.Duration;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.suggest.response.Suggest;
-import org.springframework.lang.Nullable;
 
 /**
  * Encapsulates a Flux of {@link SearchHit}s with additional information from the search.

src/main/java/org/springframework/data/elasticsearch/core/ReactiveSearchHitsImpl.java

@@ -19,8 +19,8 @@ import reactor.core.publisher.Flux;
 
 import java.time.Duration;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.suggest.response.Suggest;
-import org.springframework.lang.Nullable;
 
 /**
  * @author Peter-Josef Meisch

src/main/java/org/springframework/data/elasticsearch/core/SearchHit.java

@@ -23,9 +23,9 @@ import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.document.Explanation;
 import org.springframework.data.elasticsearch.core.document.NestedMetaData;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -48,12 +48,12 @@ public class SearchHit<T> {
 	@Nullable private final NestedMetaData nestedMetaData;
 	@Nullable private final String routing;
 	@Nullable private final Explanation explanation;
-	private final List<String> matchedQueries = new ArrayList<>();
+	private final Map<String, Double> matchedQueries = new LinkedHashMap<>();
 
 	public SearchHit(@Nullable String index, @Nullable String id, @Nullable String routing, float score,
 			@Nullable Object[] sortValues, @Nullable Map<String, List<String>> highlightFields,
 			@Nullable Map<String, SearchHits<?>> innerHits, @Nullable NestedMetaData nestedMetaData,
-			@Nullable Explanation explanation, @Nullable List<String> matchedQueries, T content) {
+			@Nullable Explanation explanation, @Nullable Map<String, Double> matchedQueries, T content) {
 		this.index = index;
 		this.id = id;
 		this.routing = routing;
@@ -73,7 +73,7 @@ public class SearchHit<T> {
 		this.content = content;
 
 		if (matchedQueries != null) {
-			this.matchedQueries.addAll(matchedQueries);
+			this.matchedQueries.putAll(matchedQueries);
 		}
 	}
 
@@ -194,7 +194,7 @@ public class SearchHit<T> {
 	 * @return the matched queries for this SearchHit.
 	 */
 	@Nullable
-	public List<String> getMatchedQueries() {
+	public Map<String, Double> getMatchedQueries() {
 		return matchedQueries;
 	}
 }

src/main/java/org/springframework/data/elasticsearch/core/SearchHitMapping.java

@@ -23,6 +23,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.UncategorizedElasticsearchException;
 import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
 import org.springframework.data.elasticsearch.core.document.Document;
@@ -34,7 +35,6 @@ import org.springframework.data.elasticsearch.core.mapping.ElasticsearchPersiste
 import org.springframework.data.elasticsearch.core.suggest.response.CompletionSuggestion;
 import org.springframework.data.elasticsearch.core.suggest.response.Suggest;
 import org.springframework.data.mapping.context.MappingContext;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/core/SearchHitSupport.java

@@ -21,11 +21,11 @@ import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.domain.PageImpl;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.util.CloseableIterator;
 import org.springframework.data.util.ReactiveWrappers;
-import org.springframework.lang.Nullable;
 
 /**
  * Utility class with helper methods for working with {@link SearchHit}.

src/main/java/org/springframework/data/elasticsearch/core/SearchHits.java

@@ -19,9 +19,9 @@ import java.time.Duration;
 import java.util.Iterator;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.suggest.response.Suggest;
 import org.springframework.data.util.Streamable;
-import org.springframework.lang.Nullable;
 
 /**
  * Encapsulates a list of {@link SearchHit}s with additional information from the search.

src/main/java/org/springframework/data/elasticsearch/core/SearchHitsImpl.java

@@ -19,9 +19,9 @@ import java.time.Duration;
 import java.util.Collections;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.suggest.response.Suggest;
 import org.springframework.data.util.Lazy;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/core/SearchHitsIterator.java

@@ -17,8 +17,8 @@ package org.springframework.data.elasticsearch.core;
 
 import java.time.Duration;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.util.CloseableIterator;
-import org.springframework.lang.Nullable;
 
 /**
  * A {@link SearchHitsIterator} encapsulates {@link SearchHit} results that can be wrapped in a Java 8

src/main/java/org/springframework/data/elasticsearch/core/SearchOperations.java

@@ -18,11 +18,11 @@ package org.springframework.data.elasticsearch.core;
 import java.time.Duration;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
 import org.springframework.data.elasticsearch.core.query.BaseQueryBuilder;
 import org.springframework.data.elasticsearch.core.query.MoreLikeThisQuery;
 import org.springframework.data.elasticsearch.core.query.Query;
-import org.springframework.lang.Nullable;
 
 /**
  * The operations for the
@@ -233,7 +233,8 @@ public interface SearchOperations {
 	Query idsQuery(List<String> ids);
 
 	/**
-	 * Creates a {@link BaseQueryBuilder} that has the given ids setto the parameter value. No other properties of the bulder are set.
+	 * Creates a {@link BaseQueryBuilder} that has the given ids setto the parameter value. No other properties of the
+	 * bulder are set.
 	 *
 	 * @param ids the list of ids must not be {@literal null}
 	 * @return query returning the documents with the given ids

src/main/java/org/springframework/data/elasticsearch/core/SearchScrollHits.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.data.elasticsearch.core;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * This interface is used to expose the current {@code scrollId} from the underlying scroll context.

src/main/java/org/springframework/data/elasticsearch/core/SearchShardStatistics.java

@@ -17,8 +17,8 @@ package org.springframework.data.elasticsearch.core;
 
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.ElasticsearchErrorCause;
-import org.springframework.lang.Nullable;
 
 /**
  * @author Haibo Liu

src/main/java/org/springframework/data/elasticsearch/core/StreamQueries.java

@@ -23,8 +23,8 @@ import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.client.util.ScrollState;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/core/cluster/package-info.java

@@ -1,6 +1,5 @@
 /**
  * Interfaces and classes related to Elasticsearch cluster information and management.
  */
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.core.cluster;

src/main/java/org/springframework/data/elasticsearch/core/convert/DefaultElasticsearchTypeMapper.java

@@ -19,6 +19,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.convert.DefaultTypeMapper;
 import org.springframework.data.convert.SimpleTypeInformationMapper;
 import org.springframework.data.convert.TypeAliasAccessor;
@@ -27,7 +28,6 @@ import org.springframework.data.mapping.Alias;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.context.MappingContext;
 import org.springframework.data.util.TypeInformation;
-import org.springframework.lang.Nullable;
 
 /**
  * Elasticsearch specific {@link org.springframework.data.convert.TypeMapper} implementation.

src/main/java/org/springframework/data/elasticsearch/core/convert/ElasticsearchConverter.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.elasticsearch.core.convert;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.convert.EntityConverter;
 import org.springframework.data.elasticsearch.core.document.Document;
 import org.springframework.data.elasticsearch.core.mapping.ElasticsearchPersistentEntity;
@@ -23,7 +24,6 @@ import org.springframework.data.elasticsearch.core.mapping.PropertyValueConverte
 import org.springframework.data.elasticsearch.core.query.Query;
 import org.springframework.data.projection.ProjectionFactory;
 import org.springframework.data.projection.SpelAwareProxyProjectionFactory;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/core/convert/ElasticsearchTypeMapper.java

@@ -17,11 +17,11 @@ package org.springframework.data.elasticsearch.core.convert;
 
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.convert.TypeMapper;
 import org.springframework.data.elasticsearch.core.mapping.ElasticsearchPersistentEntity;
 import org.springframework.data.elasticsearch.core.mapping.ElasticsearchPersistentProperty;
 import org.springframework.data.mapping.context.MappingContext;
-import org.springframework.lang.Nullable;
 
 /**
  * Elasticsearch specific {@link TypeMapper} definition.

src/main/java/org/springframework/data/elasticsearch/core/convert/MappingConversionException.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.data.elasticsearch.core.convert;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * @since 5.3

src/main/java/org/springframework/data/elasticsearch/core/convert/MappingElasticsearchConverter.java

@@ -24,6 +24,7 @@ import java.util.stream.Collectors;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.Nullable;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.ApplicationContext;
@@ -65,7 +66,6 @@ import org.springframework.data.mapping.model.*;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.format.datetime.DateFormatterRegistrar;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
@@ -394,7 +394,7 @@ public class MappingElasticsearchConverter
 				}
 
 				if (source instanceof SearchDocument searchDocument) {
-					populateScriptFields(targetEntity, result, searchDocument);
+					populateScriptedFields(targetEntity, result, searchDocument);
 				}
 				return result;
 			} catch (ConversionException e) {
@@ -652,7 +652,16 @@ public class MappingElasticsearchConverter
 			return conversionService.convert(value, target);
 		}
 
-		private <T> void populateScriptFields(ElasticsearchPersistentEntity<?> entity, T result,
+		/**
+		 * Checks if any of the properties of the entity is annotated with
+		 *
+		 * @{@link ScriptedField}. If so, the value of this property is set from the returned fields in the document.
+		 * @param entity the entity to defining the persistent property
+		 * @param result the rsult to populate
+		 * @param searchDocument the search result caontaining the fields
+		 * @param <T> the result type
+		 */
+		private <T> void populateScriptedFields(ElasticsearchPersistentEntity<?> entity, T result,
 				SearchDocument searchDocument) {
 			Map<String, List<Object>> fields = searchDocument.getFields();
 			entity.doWithProperties((SimplePropertyHandler) property -> {
@@ -661,8 +670,13 @@ public class MappingElasticsearchConverter
 					// noinspection ConstantConditions
 					String name = scriptedField.name().isEmpty() ? property.getName() : scriptedField.name();
 					if (fields.containsKey(name)) {
-						Object value = searchDocument.getFieldValue(name);
-						entity.getPropertyAccessor(result).setProperty(property, value);
+						if (property.isCollectionLike()) {
+							List<Object> values = searchDocument.getFieldValues(name);
+							entity.getPropertyAccessor(result).setProperty(property, values);
+						} else {
+							Object value = searchDocument.getFieldValue(name);
+							entity.getPropertyAccessor(result).setProperty(property, value);
+						}
 					}
 				}
 			});
@@ -1358,15 +1372,85 @@ public class MappingElasticsearchConverter
 			return;
 		}
 
-		String[] fieldNames = field.getName().split("\\.");
+		var propertyNamesUpdate = updatePropertyNames(persistentEntity, field.getName());
+
+		var fieldNames = propertyNamesUpdate.names();
+		field.setName(String.join(".", fieldNames));
+
+		if (propertyNamesUpdate.propertyCount() > 1 && propertyNamesUpdate.nestedProperty()) {
+			List<String> propertyNames = Arrays.asList(fieldNames);
+			field.setPath(String.join(".", propertyNames.subList(0, propertyNamesUpdate.propertyCount - 1)));
+		}
+
+		if (propertyNamesUpdate.persistentProperty != null) {
+
+			if (propertyNamesUpdate.persistentProperty.hasPropertyValueConverter()) {
+				PropertyValueConverter propertyValueConverter = Objects
+						.requireNonNull(propertyNamesUpdate.persistentProperty.getPropertyValueConverter());
+				criteria.getQueryCriteriaEntries().forEach(criteriaEntry -> {
+
+					if (criteriaEntry.getKey().hasValue()) {
+						Object value = criteriaEntry.getValue();
+
+						if (value.getClass().isArray()) {
+							Object[] objects = (Object[]) value;
+
+							for (int i = 0; i < objects.length; i++) {
+								objects[i] = propertyValueConverter.write(objects[i]);
+							}
+						} else {
+							criteriaEntry.setValue(propertyValueConverter.write(value));
+						}
+					}
+				});
+			}
+
+			org.springframework.data.elasticsearch.annotations.Field fieldAnnotation = propertyNamesUpdate.persistentProperty
+					.findAnnotation(org.springframework.data.elasticsearch.annotations.Field.class);
+
+			if (fieldAnnotation != null) {
+				field.setFieldType(fieldAnnotation.type());
+			}
+		}
+	}
+
+	static record PropertyNamesUpdate(
+			String[] names,
+			Boolean nestedProperty,
+			Integer propertyCount,
+			ElasticsearchPersistentProperty persistentProperty) {
+	}
+
+	@Override
+	public String updateFieldNames(String propertyPath, ElasticsearchPersistentEntity<?> persistentEntity) {
+
+		Assert.notNull(propertyPath, "propertyPath must not be null");
+		Assert.notNull(persistentEntity, "persistentEntity must not be null");
+
+		var propertyNamesUpdate = updatePropertyNames(persistentEntity, propertyPath);
+		return String.join(".", propertyNamesUpdate.names());
+	}
+
+	/**
+	 * Parse a propertyPath and replace the path values with the field names from a persistentEntity. path entries not
+	 * found in the entity are kept as they are.
+	 *
+	 * @return the eventually modified names, a flag if a nested entity was encountered the number of processed
+	 *         propertiesand the last processed PersistentProperty.
+	 */
+	PropertyNamesUpdate updatePropertyNames(ElasticsearchPersistentEntity<?> persistentEntity, String propertyPath) {
+
+		String[] propertyNames = propertyPath.split("\\.");
+		String[] fieldNames = Arrays.copyOf(propertyNames, propertyNames.length);
 
 		ElasticsearchPersistentEntity<?> currentEntity = persistentEntity;
 		ElasticsearchPersistentProperty persistentProperty = null;
+
 		int propertyCount = 0;
 		boolean isNested = false;
 
-		for (int i = 0; i < fieldNames.length; i++) {
-			persistentProperty = currentEntity.getPersistentProperty(fieldNames[i]);
+		for (int i = 0; i < propertyNames.length; i++) {
+			persistentProperty = currentEntity.getPersistentProperty(propertyNames[i]);
 
 			if (persistentProperty != null) {
 				propertyCount++;
@@ -1393,75 +1477,7 @@ public class MappingElasticsearchConverter
 			}
 		}
 
-		field.setName(String.join(".", fieldNames));
-
-		if (propertyCount > 1 && isNested) {
-			List<String> propertyNames = Arrays.asList(fieldNames);
-			field.setPath(String.join(".", propertyNames.subList(0, propertyCount - 1)));
-		}
-
-		if (persistentProperty != null) {
-
-			if (persistentProperty.hasPropertyValueConverter()) {
-				PropertyValueConverter propertyValueConverter = Objects
-						.requireNonNull(persistentProperty.getPropertyValueConverter());
-				criteria.getQueryCriteriaEntries().forEach(criteriaEntry -> {
-
-					if (criteriaEntry.getKey().hasValue()) {
-						Object value = criteriaEntry.getValue();
-
-						if (value.getClass().isArray()) {
-							Object[] objects = (Object[]) value;
-
-							for (int i = 0; i < objects.length; i++) {
-								objects[i] = propertyValueConverter.write(objects[i]);
-							}
-						} else {
-							criteriaEntry.setValue(propertyValueConverter.write(value));
-						}
-					}
-				});
-			}
-
-			org.springframework.data.elasticsearch.annotations.Field fieldAnnotation = persistentProperty
-					.findAnnotation(org.springframework.data.elasticsearch.annotations.Field.class);
-
-			if (fieldAnnotation != null) {
-				field.setFieldType(fieldAnnotation.type());
-			}
-		}
-	}
-
-	@Override
-	public String updateFieldNames(String propertyPath, ElasticsearchPersistentEntity<?> persistentEntity) {
-
-		Assert.notNull(propertyPath, "propertyPath must not be null");
-		Assert.notNull(persistentEntity, "persistentEntity must not be null");
-
-		var properties = propertyPath.split("\\.", 2);
-
-		if (properties.length > 0) {
-			var propertyName = properties[0];
-			var fieldName = propertyToFieldName(persistentEntity, propertyName);
-
-			if (properties.length > 1) {
-				var persistentProperty = persistentEntity.getPersistentProperty(propertyName);
-
-				if (persistentProperty != null) {
-					ElasticsearchPersistentEntity<?> nestedPersistentEntity = mappingContext
-							.getPersistentEntity(persistentProperty);
-					if (nestedPersistentEntity != null) {
-						return fieldName + '.' + updateFieldNames(properties[1], nestedPersistentEntity);
-					} else {
-						return fieldName;
-					}
-				}
-			}
-			return fieldName;
-		} else {
-			return propertyPath;
-		}
-
+		return new PropertyNamesUpdate(fieldNames, isNested, propertyCount, persistentProperty);
 	}
 	// endregion
 

src/main/java/org/springframework/data/elasticsearch/core/convert/package-info.java

@@ -1,3 +1,2 @@
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.core.convert;

src/main/java/org/springframework/data/elasticsearch/core/document/Document.java

@@ -20,9 +20,9 @@ import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.function.Function;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.convert.ConversionException;
 import org.springframework.data.elasticsearch.support.StringObjectMap;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/core/document/Explanation.java

@@ -18,7 +18,7 @@ package org.springframework.data.elasticsearch.core.document;
 import java.util.List;
 import java.util.Objects;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.springframework.util.Assert;
 
 /**

src/main/java/org/springframework/data/elasticsearch/core/document/MapDocument.java

@@ -21,10 +21,9 @@ import java.util.Map;
 import java.util.Set;
 import java.util.function.BiConsumer;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.support.DefaultStringObjectMap;
-import org.springframework.data.elasticsearch.support.StringObjectMap;
 import org.springframework.data.mapping.MappingException;
-import org.springframework.lang.Nullable;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;

src/main/java/org/springframework/data/elasticsearch/core/document/NestedMetaData.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.data.elasticsearch.core.document;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * meta data returned for nested inner hits.

src/main/java/org/springframework/data/elasticsearch/core/document/SearchDocument.java

@@ -18,7 +18,7 @@ package org.springframework.data.elasticsearch.core.document;
 import java.util.List;
 import java.util.Map;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Extension to {@link Document} exposing search response related data.
@@ -57,6 +57,20 @@ public interface SearchDocument extends Document {
 		return (V) values.get(0);
 	}
 
+	/**
+	 * @param name the field name
+	 * @param <V> the type of elements
+	 * @return the values of the given field.
+	 */
+	@Nullable
+	default <V> List<V> getFieldValues(final String name) {
+		List<Object> values = getFields().get(name);
+		if (values == null) {
+			return null;
+		}
+		return (List<V>) values;
+	}
+
 	/**
 	 * @return the sort values for the search hit
 	 */
@@ -111,5 +125,5 @@ public interface SearchDocument extends Document {
 	 * @return the matched queries for the SearchHit.
 	 */
 	@Nullable
-	List<String> getMatchedQueries();
+	Map<String, Double> getMatchedQueries();
 }

src/main/java/org/springframework/data/elasticsearch/core/document/SearchDocumentAdapter.java

@@ -22,7 +22,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.function.BiConsumer;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * {@link SearchDocument} implementation using a {@link Document} delegate.
@@ -41,12 +41,12 @@ public class SearchDocumentAdapter implements SearchDocument {
 	private final Map<String, SearchDocumentResponse> innerHits = new HashMap<>();
 	@Nullable private final NestedMetaData nestedMetaData;
 	@Nullable private final Explanation explanation;
-	@Nullable private final List<String> matchedQueries;
+	@Nullable private final Map<String, Double> matchedQueries;
 	@Nullable private final String routing;
 
 	public SearchDocumentAdapter(Document delegate, float score, Object[] sortValues, Map<String, List<Object>> fields,
 			Map<String, List<String>> highlightFields, Map<String, SearchDocumentResponse> innerHits,
-			@Nullable NestedMetaData nestedMetaData, @Nullable Explanation explanation, @Nullable List<String> matchedQueries,
+			@Nullable NestedMetaData nestedMetaData, @Nullable Explanation explanation, @Nullable Map<String, Double> matchedQueries,
 			@Nullable String routing) {
 
 		this.delegate = delegate;
@@ -249,7 +249,7 @@ public class SearchDocumentAdapter implements SearchDocument {
 
 	@Override
 	@Nullable
-	public List<String> getMatchedQueries() {
+	public Map<String, Double> getMatchedQueries() {
 		return matchedQueries;
 	}
 

src/main/java/org/springframework/data/elasticsearch/core/document/SearchDocumentResponse.java

@@ -20,10 +20,10 @@ import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Function;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.AggregationsContainer;
 import org.springframework.data.elasticsearch.core.SearchShardStatistics;
 import org.springframework.data.elasticsearch.core.suggest.response.Suggest;
-import org.springframework.lang.Nullable;
 
 /**
  * This represents the complete search response from Elasticsearch, including the returned documents.

src/main/java/org/springframework/data/elasticsearch/core/document/package-info.java

@@ -1,6 +1,5 @@
 /**
  * Classes related to the Document structure of Elasticsearch documents and search responses.
  */
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.core.document;

src/main/java/org/springframework/data/elasticsearch/core/event/package-info.java

@@ -1,6 +1,5 @@
 /**
  * classes and interfaces related to Spring Data Elasticsearch events and callbacks.
  */
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.core.event;

src/main/java/org/springframework/data/elasticsearch/core/geo/package-info.java

@@ -1,3 +1,2 @@
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.data.elasticsearch.core.geo;

src/main/java/org/springframework/data/elasticsearch/core/index/AliasActionParameters.java

@@ -15,8 +15,8 @@
  */
 package org.springframework.data.elasticsearch.core.index;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.query.Query;
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**