Fix handling of ResponseException from legacy client dependency.

Original Pull Request #3146
Closes #3144

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

pom.xml

@@ -5,12 +5,12 @@
 
 	<groupId>org.springframework.data</groupId>
 	<artifactId>spring-data-elasticsearch</artifactId>
-	<version>6.0.0-M4</version>
+	<version>6.0.0-SNAPSHOT</version>
 
 	<parent>
 		<groupId>org.springframework.data.build</groupId>
 		<artifactId>spring-data-parent</artifactId>
-		<version>4.0.0-M4</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>4.0.0-M4</springdata.commons>
+		<springdata.commons>4.0.0-SNAPSHOT</springdata.commons>
 
 		<!-- version of the ElasticsearchClient	-->
-		<elasticsearch-java>9.0.3</elasticsearch-java>
+		<elasticsearch-java>9.0.4</elasticsearch-java>
 
 		<hoverfly>0.19.0</hoverfly>
 		<log4j>2.23.1</log4j>
@@ -471,8 +471,20 @@
 	</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>
+		</repository>
 	</repositories>
 
 </project>

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

@@ -389,6 +389,63 @@ ClientConfiguration.builder()
 ----
 ====
 
+[[elasticsearch.clients.configurationcallbacks.connectionconfig]]
+==== Configuration of the ConnectionConfig used by the low level Elasticsearch `Rest5Client`:
+
+This callback provides a `org.apache.hc.client5.http.config.ConnectionConfig` to configure the connection that is
+used by the `Rest5Client`.
+
+====
+[source,java]
+----
+ClientConfiguration.builder()
+    .connectedTo("localhost:9200", "localhost:9291")
+    .withClientConfigurer(Rest5Clients.ElasticsearchConnectionConfigurationCallback.from(connectionConfigBuilder -> {
+        // configure the connection
+        return connectionConfigBuilder;
+    }))
+    .build();
+----
+====
+
+[[elasticsearch.clients.configurationcallbacks.connectioncmanager]]
+==== Configuration of the ConnectionManager used by the low level Elasticsearch `Rest5Client`:
+
+This callback provides a `org.apache.hc.client5.http.impl.nio.PoolingAsyncClientConnectionManagerBuilder` to configure the connection manager that is
+used by the `Rest5Client`.
+
+====
+[source,java]
+----
+ClientConfiguration.builder()
+    .connectedTo("localhost:9200", "localhost:9291")
+    .withClientConfigurer(Rest5Clients.ElasticsearchConnectionManagerCallback.from(connectionManagerBuilder -> {
+        // configure the connection manager
+        return connectionManagerBuilder;
+    }))
+    .build();
+----
+====
+
+[[elasticsearch.clients.configurationcallbacks.requestconfig]]
+==== Configuration of the RequestConfig used by the low level Elasticsearch `Rest5Client`:
+
+This callback provides a `org.apache.hc.client5.http.config.RequestConfig` to configure the RequestConfig that is
+used by the `Rest5Client`.
+
+====
+[source,java]
+----
+ClientConfiguration.builder()
+    .connectedTo("localhost:9200", "localhost:9291")
+    .withClientConfigurer(Rest5Clients.ElasticsearchRequestConfigCallback.from(requestConfigBuilder -> {
+        // configure the request config
+        return requestConfigBuilder;
+    }))
+    .build();
+----
+====
+
 [[elasticsearch.clients.logging]]
 == Client Logging
 

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

@@ -6,7 +6,7 @@
 
 * Upgarde to Spring 7
 * Switch to jspecify nullability annotations
-* Upgrade to Elasticsearch 9.0.3
+* Upgrade to Elasticsearch 9.0.4
 * Use the new Elasticsearch Rest5Client as default
 
 

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

@@ -6,7 +6,7 @@ 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
-| 2025.1 (in development) | 6.0.x | 9.0.3 | 7.0.x
+| 2025.1 (in development) | 6.0.x | 9.0.4 | 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.xfootnote:oom[Out of maintenance] | 8.13.4 | 6.1.x

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

@@ -8,6 +8,8 @@ This section describes breaking changes from version 5.5.x to 6.0.x and how remo
 
 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
 

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

@@ -24,6 +24,7 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import org.elasticsearch.client.ResponseException;
+import org.jspecify.annotations.Nullable;
 import org.springframework.dao.DataAccessException;
 import org.springframework.dao.DataAccessResourceFailureException;
 import org.springframework.dao.DataIntegrityViolationException;
@@ -33,6 +34,7 @@ import org.springframework.data.elasticsearch.NoSuchIndexException;
 import org.springframework.data.elasticsearch.ResourceNotFoundException;
 import org.springframework.data.elasticsearch.UncategorizedElasticsearchException;
 import org.springframework.data.elasticsearch.VersionConflictException;
+import org.springframework.util.ClassUtils;
 
 /**
  * Simple {@link PersistenceExceptionTranslator} for Elasticsearch. Convert the given runtime exception to an
@@ -45,6 +47,9 @@ import org.springframework.data.elasticsearch.VersionConflictException;
  */
 public class ElasticsearchExceptionTranslator implements PersistenceExceptionTranslator {
 
+	public static final boolean LEGACY_RESTCLIENT_PRESENT = ClassUtils
+			.isPresent("org.elasticsearch.client.ResponseException", ElasticsearchExceptionTranslator.class.getClassLoader());
+
 	private final JsonpMapper jsonpMapper;
 
 	public ElasticsearchExceptionTranslator(JsonpMapper jsonpMapper) {
@@ -68,7 +73,7 @@ public class ElasticsearchExceptionTranslator implements PersistenceExceptionTra
 	}
 
 	@Override
-	public DataAccessException translateExceptionIfPossible(RuntimeException ex) {
+	public @Nullable DataAccessException translateExceptionIfPossible(RuntimeException ex) {
 
 		checkForConflictException(ex);
 
@@ -118,7 +123,7 @@ public class ElasticsearchExceptionTranslator implements PersistenceExceptionTra
 		Integer status = null;
 		String message = null;
 
-		if (exception instanceof ResponseException responseException) {
+		if (LEGACY_RESTCLIENT_PRESENT && exception instanceof ResponseException responseException) {
 			// this code is for the old RestClient
 			status = responseException.getResponse().getStatusLine().getStatusCode();
 			message = responseException.getMessage();

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

@@ -658,7 +658,7 @@ public class ElasticsearchTemplate extends AbstractElasticsearchTemplate {
 			QueryResponse response = sqlClient.query(requestConverter.sqlQueryRequest(query));
 
 			return responseConverter.sqlResponse(response);
-		} catch (IOException e) {
+		} catch (Exception e) {
 			throw exceptionTranslator.translateException(e);
 		}
 	}

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

@@ -25,6 +25,7 @@ import co.elastic.clients.elasticsearch.core.search.ResponseBody;
 import co.elastic.clients.json.JsonpMapper;
 import co.elastic.clients.transport.Version;
 import co.elastic.clients.transport.endpoints.BooleanResponse;
+import org.jspecify.annotations.NonNull;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.util.function.Tuple2;
@@ -162,7 +163,7 @@ public class ReactiveElasticsearchTemplate extends AbstractReactiveElasticsearch
 		ExistsRequest existsRequest = requestConverter.documentExistsRequest(id, routingResolver.getRouting(), index);
 
 		return Mono.from(execute(
-				((ClientCallback<Publisher<BooleanResponse>>) client -> client.exists(existsRequest))))
+				((ClientCallback<@NonNull Publisher<BooleanResponse>>) client -> client.exists(existsRequest))))
 				.map(BooleanResponse::value) //
 				.onErrorReturn(NoSuchIndexException.class, false);
 	}

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

@@ -723,12 +723,11 @@ 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
 
@@ -1095,17 +1094,16 @@ class RequestConverter extends AbstractQueryProcessor {
 				});
 			}
 
-			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()));
@@ -1293,7 +1291,7 @@ class RequestConverter extends AbstractQueryProcessor {
 									.timeout(timeStringMs(query.getTimeout())) //
 							;
 
-                            bb.from((int) (query.getPageable().isPaged() ? query.getPageable().getOffset() : 0))
+							bb.from((int) (query.getPageable().isPaged() ? query.getPageable().getOffset() : 0))
 									.size(query.getRequestSize());
 
 							if (!isEmpty(query.getFields())) {
@@ -1466,7 +1464,7 @@ class RequestConverter extends AbstractQueryProcessor {
 			builder.seqNoPrimaryTerm(true);
 		}
 
-        builder.from((int) (query.getPageable().isPaged() ? query.getPageable().getOffset() : 0))
+		builder.from((int) (query.getPageable().isPaged() ? query.getPageable().getOffset() : 0))
 				.size(query.getRequestSize());
 
 		if (!isEmpty(query.getFields())) {

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

@@ -13,20 +13,14 @@ 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;
@@ -38,7 +32,6 @@ 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;
 
 /**
@@ -49,11 +42,8 @@ import org.springframework.util.Assert;
 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() {}
 
@@ -82,11 +72,7 @@ public final class Rest5Clients {
 			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);
-
+		// RestClientBuilder configuration callbacks from the consumer
 		for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurationCallback : clientConfiguration
 				.getClientConfigurers()) {
 			if (clientConfigurationCallback instanceof ElasticsearchRest5ClientConfigurationCallback configurationCallback) {
@@ -94,6 +80,104 @@ public final class Rest5Clients {
 			}
 		}
 
+		Duration connectTimeout = clientConfiguration.getConnectTimeout();
+		Duration socketTimeout = clientConfiguration.getSocketTimeout();
+
+		builder.setHttpClientConfigCallback(httpAsyncClientBuilder -> {
+
+			if (clientConfiguration.getProxy().isPresent()) {
+				var proxy = clientConfiguration.getProxy().get();
+				try {
+					var proxyRoutePlanner = new DefaultProxyRoutePlanner(HttpHost.create(proxy));
+					httpAsyncClientBuilder.setRoutePlanner(proxyRoutePlanner);
+				} catch (URISyntaxException e) {
+					throw new RuntimeException(e);
+				}
+			}
+			httpAsyncClientBuilder.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));
+				});
+			});
+
+			// add httpclient configurator callbacks provided by the configuration
+			for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurer : clientConfiguration
+					.getClientConfigurers()) {
+				if (clientConfigurer instanceof ElasticsearchHttpClientConfigurationCallback httpClientConfigurer) {
+					httpAsyncClientBuilder = httpClientConfigurer.configure(httpAsyncClientBuilder);
+				}
+			}
+		});
+
+		builder.setConnectionConfigCallback(connectionConfigBuilder -> {
+
+			if (!connectTimeout.isNegative()) {
+				connectionConfigBuilder.setConnectTimeout(
+						Timeout.of(Math.toIntExact(connectTimeout.toMillis()), TimeUnit.MILLISECONDS));
+			}
+			if (!socketTimeout.isNegative()) {
+				var soTimeout = Timeout.of(Math.toIntExact(socketTimeout.toMillis()), TimeUnit.MILLISECONDS);
+				connectionConfigBuilder.setSocketTimeout(soTimeout);
+			} else {
+				connectionConfigBuilder.setSocketTimeout(Timeout.of(DEFAULT_SOCKET_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS));
+			}
+
+			// add connectionConfig configurator callbacks provided by the configuration
+			for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurer : clientConfiguration
+					.getClientConfigurers()) {
+				if (clientConfigurer instanceof ElasticsearchConnectionConfigurationCallback connectionConfigurationCallback) {
+					connectionConfigBuilder = connectionConfigurationCallback.configure(connectionConfigBuilder);
+				}
+			}
+		});
+
+		builder.setConnectionManagerCallback(poolingAsyncClientConnectionManagerBuilder -> {
+
+			SSLContext sslContext = null;
+			try {
+				sslContext = clientConfiguration.getCaFingerprint().isPresent()
+						? TransportUtils.sslContextFromCaFingerprint(clientConfiguration.getCaFingerprint().get())
+						: (clientConfiguration.getSslContext().isPresent()
+								? clientConfiguration.getSslContext().get()
+								: SSLContext.getDefault());
+			} catch (NoSuchAlgorithmException e) {
+				throw new IllegalStateException("could not create the default ssl context", e);
+			}
+			poolingAsyncClientConnectionManagerBuilder.setTlsStrategy(new BasicClientTlsStrategy(sslContext));
+
+			// add connectionManager configurator callbacks provided by the configuration
+			for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurer : clientConfiguration
+					.getClientConfigurers()) {
+				if (clientConfigurer instanceof ElasticsearchConnectionManagerCallback connectionManagerCallback) {
+					poolingAsyncClientConnectionManagerBuilder = connectionManagerCallback
+							.configure(poolingAsyncClientConnectionManagerBuilder);
+				}
+			}
+		});
+
+		builder.setRequestConfigCallback(requestConfigBuilder -> {
+
+			if (!socketTimeout.isNegative()) {
+				var soTimeout = Timeout.of(Math.toIntExact(socketTimeout.toMillis()), TimeUnit.MILLISECONDS);
+				requestConfigBuilder.setConnectionRequestTimeout(soTimeout);
+			} else {
+				requestConfigBuilder
+						.setConnectionRequestTimeout(Timeout.of(DEFAULT_RESPONSE_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS));
+			}
+			// add connectionConfig configurator callbacks provided by the configuration
+			for (ClientConfiguration.ClientConfigurationCallback<?> clientConfigurer : clientConfiguration
+					.getClientConfigurers()) {
+				if (clientConfigurer instanceof ElasticsearchRequestConfigCallback requestConfigCallback) {
+					requestConfigBuilder = requestConfigCallback.configure(requestConfigBuilder);
+				}
+			}
+		});
+
 		return builder;
 	}
 
@@ -114,109 +198,23 @@ public final class Rest5Clients {
 				.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.
+	/**
+	 * {@link ClientConfiguration.ClientConfigurationCallback} to configure the Rest5Client client with a
+	 * {@link Rest5ClientBuilder}
+	 *
+	 * @since 6.0
 	 */
-	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;
+	public interface ElasticsearchRest5ClientConfigurationCallback
+			extends ClientConfiguration.ClientConfigurationCallback<Rest5ClientBuilder> {
 
-		private RestClientThreadFactory() {
-			this.clientThreadPoolId = CLIENT_THREAD_POOL_ID_GENERATOR.getAndIncrement();
-			this.clientThreadId = new AtomicLong();
+		static ElasticsearchRest5ClientConfigurationCallback from(
+				Function<Rest5ClientBuilder, Rest5ClientBuilder> rest5ClientBuilderCallback) {
+
+			Assert.notNull(rest5ClientBuilderCallback, "rest5ClientBuilderCallback must not be null");
+
+			return rest5ClientBuilderCallback::apply;
 		}
 
-		public Thread newThread(Runnable runnable) {
-			return new Thread(runnable, String.format(Locale.ROOT, "elasticsearch-rest-client-%d-thread-%d",
-					this.clientThreadPoolId, this.clientThreadId.incrementAndGet()));
-		}
 	}
 
 	/**
@@ -238,20 +236,56 @@ public final class Rest5Clients {
 	}
 
 	/**
-	 * {@link ClientConfiguration.ClientConfigurationCallback} to configure the Rest5Client client with a
-	 * {@link Rest5ClientBuilder}
+	 * {@link org.springframework.data.elasticsearch.client.ClientConfiguration.ClientConfigurationCallback} to configure
+	 * the Elasticsearch Rest5Client's connection with a {@link ConnectionConfig.Builder}
 	 *
 	 * @since 6.0
 	 */
-	public interface ElasticsearchRest5ClientConfigurationCallback
-			extends ClientConfiguration.ClientConfigurationCallback<Rest5ClientBuilder> {
+	public interface ElasticsearchConnectionConfigurationCallback
+			extends ClientConfiguration.ClientConfigurationCallback<ConnectionConfig.Builder> {
 
-		static ElasticsearchRest5ClientConfigurationCallback from(
-				Function<Rest5ClientBuilder, Rest5ClientBuilder> rest5ClientBuilderCallback) {
+		static ElasticsearchConnectionConfigurationCallback from(
+				Function<ConnectionConfig.Builder, ConnectionConfig.Builder> connectionConfigBuilderCallback) {
 
-			Assert.notNull(rest5ClientBuilderCallback, "rest5ClientBuilderCallback must not be null");
+			Assert.notNull(connectionConfigBuilderCallback, "connectionConfigBuilderCallback must not be null");
 
-			return rest5ClientBuilderCallback::apply;
+			return connectionConfigBuilderCallback::apply;
+		}
+	}
+
+	/**
+	 * {@link org.springframework.data.elasticsearch.client.ClientConfiguration.ClientConfigurationCallback} to configure
+	 * the Elasticsearch Rest5Client's connection manager with a {@link PoolingAsyncClientConnectionManagerBuilder}
+	 *
+	 * @since 6.0
+	 */
+	public interface ElasticsearchConnectionManagerCallback
+			extends ClientConfiguration.ClientConfigurationCallback<PoolingAsyncClientConnectionManagerBuilder> {
+
+		static ElasticsearchConnectionManagerCallback from(
+				Function<PoolingAsyncClientConnectionManagerBuilder, PoolingAsyncClientConnectionManagerBuilder> connectionManagerBuilderCallback) {
+
+			Assert.notNull(connectionManagerBuilderCallback, "connectionManagerBuilderCallback must not be null");
+
+			return connectionManagerBuilderCallback::apply;
+		}
+	}
+
+	/**
+	 * {@link org.springframework.data.elasticsearch.client.ClientConfiguration.ClientConfigurationCallback} to configure
+	 * the Elasticsearch Rest5Client's connection manager with a {@link RequestConfig.Builder}
+	 *
+	 * @since 6.0
+	 */
+	public interface ElasticsearchRequestConfigCallback
+			extends ClientConfiguration.ClientConfigurationCallback<RequestConfig.Builder> {
+
+		static ElasticsearchRequestConfigCallback from(
+				Function<RequestConfig.Builder, RequestConfig.Builder> requestConfigBuilderCallback) {
+
+			Assert.notNull(requestConfigBuilderCallback, "requestConfigBuilderCallback must not be null");
+
+			return requestConfigBuilderCallback::apply;
 		}
 	}
 

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.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.data.elasticsearch.core.convert.ElasticsearchConverter;
@@ -369,7 +370,7 @@ public class EntityOperations {
 		 * @see org.springframework.data.elasticsearch.core.EntityOperations.AdaptableEntity#initializeVersionProperty()
 		 */
 		@Override
-		public T initializeVersionProperty() {
+		public @NonNull T initializeVersionProperty() {
 			return map;
 		}
 
@@ -389,7 +390,7 @@ public class EntityOperations {
 		}
 
 		@Override
-		public SeqNoPrimaryTerm getSeqNoPrimaryTerm() {
+		public @Nullable SeqNoPrimaryTerm getSeqNoPrimaryTerm() {
 			return null;
 		}
 
@@ -398,7 +399,7 @@ public class EntityOperations {
 		 * @see org.springframework.data.elasticsearch.core.EntityOperations.AdaptableEntity#incrementVersion()
 		 */
 		@Override
-		public T incrementVersion() {
+		public @NonNull T incrementVersion() {
 			return map;
 		}
 
@@ -407,7 +408,7 @@ public class EntityOperations {
 		 * @see org.springframework.data.elasticsearch.core.EntityOperations.Entity#getBean()
 		 */
 		@Override
-		public T getBean() {
+		public @NonNull T getBean() {
 			return map;
 		}
 
@@ -425,12 +426,12 @@ public class EntityOperations {
 		 * @see org.springframework.data.elasticsearch.core.EntityOperations.Entity#getPersistentEntity()
 		 */
 		@Override
-		public ElasticsearchPersistentEntity<?> getPersistentEntity() {
+		public @Nullable ElasticsearchPersistentEntity<?> getPersistentEntity() {
 			return null;
 		}
 
 		@Override
-		public String getRouting() {
+		public @Nullable String getRouting() {
 			return null;
 		}
 	}
@@ -650,7 +651,7 @@ public class EntityOperations {
 		}
 
 		@Override
-		public String getRouting() {
+		public @Nullable String getRouting() {
 
 			String routing = routingResolver.getRouting(propertyAccessor.getBean());
 

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

@@ -714,7 +714,7 @@ public class MappingElasticsearchConverter
 			}
 
 			@Override
-			public <T> T getPropertyValue(ElasticsearchPersistentProperty property) {
+			public <T> @Nullable T getPropertyValue(ElasticsearchPersistentProperty property) {
 
 				String expression = property.getSpelExpression();
 				Object value = expression != null ? evaluator.evaluate(expression) : accessor.get(property);

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

@@ -66,8 +66,7 @@ public class AliasActionParameters {
 		return indices;
 	}
 
-	@Nullable
-	public String[] getAliases() {
+	public String@Nullable[] getAliases() {
 		return aliases;
 	}
 
@@ -107,8 +106,8 @@ public class AliasActionParameters {
 	}
 
 	public static final class Builder {
-		@Nullable private String[] indices;
-		@Nullable private String[] aliases;
+		private String @Nullable [] indices;
+		private String @Nullable [] aliases;
 		@Nullable private Query filterQuery;
 		@Nullable private Class<?> filterQueryClass;
 		@Nullable private Boolean isHidden;

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

@@ -55,6 +55,7 @@ public class AliasActions {
 	public AliasActions add(@Nullable AliasAction... actions) {
 
 		if (actions != null) {
+			// noinspection NullableProblems
 			this.actions.addAll(Arrays.asList(actions));
 		}
 

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

@@ -29,6 +29,7 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.data.annotation.Transient;
@@ -273,7 +274,7 @@ public class MappingBuilder {
 			writeTypeHintMapping(propertiesNode);
 
 			if (entity != null) {
-				entity.doWithProperties((PropertyHandler<ElasticsearchPersistentProperty>) property -> {
+				entity.doWithProperties((PropertyHandler<@NonNull ElasticsearchPersistentProperty>) property -> {
 					try {
 						if (property.isAnnotationPresent(Transient.class) || isInIgnoreFields(property, parentFieldAnnotation)) {
 							return;

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

@@ -35,7 +35,7 @@ public record PutIndexTemplateRequest(String name, String[] indexPatterns, @Null
 	public static class Builder {
 
 		@Nullable private String name;
-		@Nullable private String[] indexPatterns;
+		private String @Nullable [] indexPatterns;
 		@Nullable private Settings settings;
 		@Nullable private Document mapping;
 		@Nullable AliasActions aliasActions;

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

@@ -81,7 +81,7 @@ public class TemplateData {
 		@Nullable Document mapping;
 		int order;
 		@Nullable Integer version;
-		@Nullable private String[] indexPatterns;
+		@Nullable private String@Nullable [] indexPatterns;
 		@Nullable private Map<String, AliasData> aliases;
 
 		private TemplateDataBuilder() {}

src/main/java/org/springframework/data/elasticsearch/core/mapping/ElasticsearchPersistentEntity.java

@@ -65,7 +65,7 @@ public interface ElasticsearchPersistentEntity<T> extends PersistentEntity<T, El
 	String getIndexStoreType();
 
 	@Override
-	ElasticsearchPersistentProperty getVersionProperty();
+	@Nullable ElasticsearchPersistentProperty getVersionProperty();
 
 	@Nullable
 	String settingPath();

src/main/java/org/springframework/data/elasticsearch/core/mapping/SimpleElasticsearchPersistentEntity.java

@@ -23,6 +23,7 @@ import java.util.concurrent.atomic.AtomicReference;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
@@ -298,7 +299,7 @@ public class SimpleElasticsearchPersistentEntity<T> extends BasicPersistentEntit
 
 		return fieldNamePropertyCache.computeIfAbsent(fieldName, key -> {
 			AtomicReference<ElasticsearchPersistentProperty> propertyRef = new AtomicReference<>();
-			doWithProperties((PropertyHandler<ElasticsearchPersistentProperty>) property -> {
+			doWithProperties((PropertyHandler<@NonNull ElasticsearchPersistentProperty>) property -> {
 				if (key.equals(property.getFieldName())) {
 					propertyRef.set(property);
 				}
@@ -552,10 +553,10 @@ public class SimpleElasticsearchPersistentEntity<T> extends BasicPersistentEntit
 		short replicas;
 		@Nullable String refreshIntervall;
 		@Nullable String indexStoreType;
-		@Nullable private String[] sortFields;
-		private Setting.@Nullable SortOrder[] sortOrders;
-		private Setting.@Nullable SortMode[] sortModes;
-		private Setting.@Nullable SortMissing[] sortMissingValues;
+		private String @Nullable [] sortFields;
+		private Setting.@Nullable SortOrder @Nullable [] sortOrders;
+		private Setting.@Nullable SortMode @Nullable [] sortModes;
+		private Setting.@Nullable SortMissing @Nullable [] sortMissingValues;
 
 		Settings toSettings() {
 

src/main/java/org/springframework/data/elasticsearch/core/query/BaseQueryBuilder.java

@@ -200,7 +200,7 @@ public abstract class BaseQueryBuilder<Q extends BaseQuery, SELF extends BaseQue
 	/**
 	 * @since 5.1
 	 */
-	public Integer getReactiveBatchSize() {
+	public @Nullable Integer getReactiveBatchSize() {
 		return reactiveBatchSize;
 	}
 

src/main/java/org/springframework/data/elasticsearch/core/query/ByQueryResponse.java

@@ -344,8 +344,8 @@ public class ByQueryResponse {
 		 *
 		 * @return a new {@link SearchFailureBuilder} to build {@link SearchFailure}
 		 */
-		public static SearchFailureBuilder builder() {
-			return new SearchFailureBuilder();
+		public static SearchFailureBuilder builder(Throwable reason) {
+			return new SearchFailureBuilder(reason);
 		}
 
 		/**
@@ -358,7 +358,9 @@ public class ByQueryResponse {
 			@Nullable private Integer shardId;
 			@Nullable private String nodeId;
 
-			private SearchFailureBuilder() {}
+			private SearchFailureBuilder(Throwable reason) {
+				this.reason = reason;
+			}
 
 			public SearchFailureBuilder withReason(Throwable reason) {
 				this.reason = reason;

src/main/java/org/springframework/data/elasticsearch/core/query/FetchSourceFilter.java

@@ -63,12 +63,12 @@ public class FetchSourceFilter implements SourceFilter {
 	}
 
 	@Override
-	public String[] getIncludes() {
+	public @Nullable String[] getIncludes() {
 		return includes;
 	}
 
 	@Override
-	public String[] getExcludes() {
+	public @Nullable String[] getExcludes() {
 		return excludes;
 	}
 }

src/main/java/org/springframework/data/elasticsearch/core/query/FetchSourceFilterBuilder.java

@@ -26,8 +26,8 @@ import org.jspecify.annotations.Nullable;
 public class FetchSourceFilterBuilder {
 
 	@Nullable private Boolean fetchSource;
-	@Nullable private String[] includes;
-	@Nullable private String[] excludes;
+	private String @Nullable [] includes;
+	private String @Nullable [] excludes;
 
 	public FetchSourceFilterBuilder withIncludes(String... includes) {
 		this.includes = includes;

src/main/java/org/springframework/data/elasticsearch/core/query/GeoDistanceOrder.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.elasticsearch.core.query;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.elasticsearch.core.geo.GeoPoint;
 
@@ -92,7 +93,7 @@ public class GeoDistanceOrder extends Order {
 				getIgnoreUnmapped());
 	}
 
-	public GeoDistanceOrder with(Mode mode) {
+	public GeoDistanceOrder with(@Nullable Mode mode) {
 		return new GeoDistanceOrder(getProperty(), getGeoPoint(), getDirection(), getDistanceType(), mode, getUnit(),
 				getIgnoreUnmapped());
 	}

src/main/java/org/springframework/data/elasticsearch/core/query/HasChildQuery.java

@@ -121,7 +121,7 @@ public class HasChildQuery {
 
 	public static final class Builder {
 		private final String type;
-		private Query query;
+		@Nullable private Query query;
 
 		@Nullable private Boolean ignoreUnmapped;
 

src/main/java/org/springframework/data/elasticsearch/core/query/HasParentQuery.java

@@ -92,7 +92,7 @@ public class HasParentQuery {
 
 	public static class Builder {
 		private final String parentType;
-		private Query query;
+		@Nullable private Query query;
 
 		@Nullable private Boolean score;
 		@Nullable private Boolean ignoreUnmapped;

src/main/java/org/springframework/data/elasticsearch/core/query/SourceFilter.java

@@ -32,14 +32,14 @@ public interface SourceFilter {
 	/**
 	 * @return the name of the fields to include in a response.
 	 */
-	@Nullable
-	String[] getIncludes();
+
+	String@Nullable[] getIncludes();
 
 	/**
 	 * @return the names of the fields to exclude from a response.
 	 */
-	@Nullable
-	String[] getExcludes();
+
+	String@Nullable[] getExcludes();
 
 	/**
 	 * Flag to set the _source parameter in a query to true or false. If this is not null, the values returned from

src/main/java/org/springframework/data/elasticsearch/core/query/UpdateQuery.java

@@ -42,8 +42,8 @@ public class UpdateQuery {
 	@Nullable private final Boolean fetchSource;
 	@Nullable private final List<String> fetchSourceIncludes;
 	@Nullable private final List<String> fetchSourceExcludes;
-	@Nullable private final Integer ifSeqNo;
-	@Nullable private final Integer ifPrimaryTerm;
+	@Nullable private final Long ifSeqNo;
+	@Nullable private final Long ifPrimaryTerm;
 	@Nullable private final RefreshPolicy refreshPolicy;
 	@Nullable private final Integer retryOnConflict;
 	@Nullable private final String timeout;
@@ -71,8 +71,8 @@ public class UpdateQuery {
 	private UpdateQuery(String id, @Nullable String script, @Nullable Map<String, Object> params,
 			@Nullable Document document, @Nullable Document upsert, @Nullable String lang, @Nullable String routing,
 			@Nullable Boolean scriptedUpsert, @Nullable Boolean docAsUpsert, @Nullable Boolean fetchSource,
-			@Nullable List<String> fetchSourceIncludes, @Nullable List<String> fetchSourceExcludes, @Nullable Integer ifSeqNo,
-			@Nullable Integer ifPrimaryTerm, @Nullable RefreshPolicy refreshPolicy, @Nullable Integer retryOnConflict,
+			@Nullable List<String> fetchSourceIncludes, @Nullable List<String> fetchSourceExcludes, @Nullable Long ifSeqNo,
+			@Nullable Long ifPrimaryTerm, @Nullable RefreshPolicy refreshPolicy, @Nullable Integer retryOnConflict,
 			@Nullable String timeout, @Nullable String waitForActiveShards, @Nullable Query query,
 			@Nullable Boolean abortOnVersionConflict, @Nullable Integer batchSize, @Nullable Integer maxDocs,
 			@Nullable Integer maxRetries, @Nullable String pipeline, @Nullable Float requestsPerSecond,
@@ -172,12 +172,12 @@ public class UpdateQuery {
 	}
 
 	@Nullable
-	public Integer getIfSeqNo() {
+	public Long getIfSeqNo() {
 		return ifSeqNo;
 	}
 
 	@Nullable
-	public Integer getIfPrimaryTerm() {
+	public Long getIfPrimaryTerm() {
 		return ifPrimaryTerm;
 	}
 
@@ -268,7 +268,7 @@ public class UpdateQuery {
 	}
 
 	public static final class Builder {
-		private String id;
+		private String id = "";
 		@Nullable private String script = null;
 		@Nullable private Map<String, Object> params;
 		@Nullable private Document document = null;
@@ -278,8 +278,8 @@ public class UpdateQuery {
 		@Nullable private Boolean scriptedUpsert;
 		@Nullable private Boolean docAsUpsert;
 		@Nullable private Boolean fetchSource;
-		@Nullable private Integer ifSeqNo;
-		@Nullable private Integer ifPrimaryTerm;
+		@Nullable private Long ifSeqNo;
+		@Nullable private Long ifPrimaryTerm;
 		@Nullable private RefreshPolicy refreshPolicy;
 		@Nullable private Integer retryOnConflict;
 		@Nullable private String timeout;
@@ -351,12 +351,12 @@ public class UpdateQuery {
 			return this;
 		}
 
-		public Builder withIfSeqNo(Integer ifSeqNo) {
+		public Builder withIfSeqNo(Long ifSeqNo) {
 			this.ifSeqNo = ifSeqNo;
 			return this;
 		}
 
-		public Builder withIfPrimaryTerm(Integer ifPrimaryTerm) {
+		public Builder withIfPrimaryTerm(Long ifPrimaryTerm) {
 			this.ifPrimaryTerm = ifPrimaryTerm;
 			return this;
 		}

src/main/java/org/springframework/data/elasticsearch/repository/query/ReactiveRepositorySearchTemplateQuery.java

@@ -18,6 +18,7 @@ package org.springframework.data.elasticsearch.repository.query;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.springframework.data.elasticsearch.core.ReactiveElasticsearchOperations;
 import org.springframework.data.elasticsearch.core.query.BaseQuery;
 import org.springframework.data.elasticsearch.core.query.SearchTemplateQuery;
@@ -33,7 +34,7 @@ import org.springframework.util.Assert;
 public class ReactiveRepositorySearchTemplateQuery extends AbstractReactiveElasticsearchRepositoryQuery {
 
 	private String id;
-	private Map<String, Object> params;
+	private Map<String, Object> params = Map.of();
 
 	public ReactiveRepositorySearchTemplateQuery(ReactiveElasticsearchQueryMethod queryMethod,
 			ReactiveElasticsearchOperations elasticsearchOperations,

src/main/java/org/springframework/data/elasticsearch/repository/query/RepositorySearchTemplateQuery.java

@@ -33,7 +33,7 @@ import org.springframework.util.Assert;
 public class RepositorySearchTemplateQuery extends AbstractElasticsearchRepositoryQuery {
 
 	private String id;
-	private Map<String, Object> params;
+	private Map<String, Object> params = Map.of();
 
 	public RepositorySearchTemplateQuery(ElasticsearchQueryMethod queryMethod,
 			ElasticsearchOperations elasticsearchOperations, ValueExpressionDelegate valueExpressionDelegate,

src/main/java/org/springframework/data/elasticsearch/repository/support/querybyexample/ExampleCriteriaMapper.java

@@ -82,7 +82,7 @@ class ExampleCriteriaMapper {
 
 			Object propertyValue = propertyAccessor.getProperty(property);
 			if (property.isMap() && propertyValue != null) {
-				for (Map.Entry<String, Object> entry : ((Map<String, Object>) propertyValue).entrySet()) {
+				for (Map.Entry<String, @Nullable Object> entry : ((Map<String, @Nullable Object>) propertyValue).entrySet()) {
 					String key = entry.getKey();
 					Object value = entry.getValue();
 					criteria = applyPropertySpec(propertyPath + "." + key, value, exampleSpecAccessor, property, matchMode,
@@ -96,7 +96,7 @@ class ExampleCriteriaMapper {
 		return criteria;
 	}
 
-	private Criteria applyPropertySpec(String path, Object propertyValue, ExampleMatcherAccessor exampleSpecAccessor,
+	private Criteria applyPropertySpec(String path, @Nullable Object propertyValue, ExampleMatcherAccessor exampleSpecAccessor,
 			ElasticsearchPersistentProperty property, ExampleMatcher.MatchMode matchMode, Criteria criteria) {
 
 		if (exampleSpecAccessor.isIgnoreCaseForPath(path)) {

src/main/java/org/springframework/data/elasticsearch/repository/support/querybyexample/QueryByExampleElasticsearchExecutor.java

@@ -47,13 +47,14 @@ public class QueryByExampleElasticsearchExecutor<T> implements QueryByExampleExe
 
 	@Override
 	public <S extends T> Optional<S> findOne(Example<S> example) {
-		CriteriaQuery criteriaQuery = CriteriaQuery.builder(exampleCriteriaMapper.criteria(example)).withMaxResults(2).build();
+		CriteriaQuery criteriaQuery = CriteriaQuery.builder(exampleCriteriaMapper.criteria(example)).withMaxResults(2)
+				.build();
 		SearchHits<S> searchHits = operations.search(criteriaQuery, example.getProbeType(),
 				operations.getIndexCoordinatesFor(example.getProbeType()));
 		if (searchHits.getTotalHits() > 1) {
 			throw new org.springframework.dao.IncorrectResultSizeDataAccessException(1);
 		}
-		return Optional.ofNullable(searchHits).filter(SearchHits::hasSearchHits)
+		return Optional.of(searchHits).filter(SearchHits::hasSearchHits)
 				.map(result -> (List<S>) SearchHitSupport.unwrapSearchHits(result)).map(s -> s.get(0));
 	}
 

src/main/java/org/springframework/data/elasticsearch/support/HttpHeaders.java

@@ -39,11 +39,11 @@ import org.springframework.util.MultiValueMapAdapter;
  * @author Peter-Josef Meisch
  * @since 5.0
  */
-public class HttpHeaders implements MultiValueMap<String, String> {
+public class HttpHeaders implements MultiValueMap<String, @Nullable String> {
 
 	public static final String AUTHORIZATION = "Authorization";
 
-	private final MultiValueMap<String, String> delegate;
+	private final MultiValueMap<String, @Nullable String> delegate;
 
 	public HttpHeaders() {
 		this.delegate = new MultiValueMapAdapter<>(new LinkedCaseInsensitiveMap<>(Locale.ENGLISH));
@@ -62,12 +62,12 @@ public class HttpHeaders implements MultiValueMap<String, String> {
 	}
 
 	@Override
-	public void addAll(String key, List<? extends String> values) {
+	public void addAll(String key, List<? extends @Nullable String> values) {
 		delegate.addAll(key, values);
 	}
 
 	@Override
-	public void addAll(MultiValueMap<String, String> values) {
+	public void addAll(MultiValueMap<String, @Nullable String> values) {
 		delegate.addAll(values);
 	}
 
@@ -77,12 +77,12 @@ public class HttpHeaders implements MultiValueMap<String, String> {
 	}
 
 	@Override
-	public void setAll(Map<String, String> values) {
+	public void setAll(Map<String, @Nullable String> values) {
 		delegate.setAll(values);
 	}
 
 	@Override
-	public Map<String, String> toSingleValueMap() {
+	public Map<String, @Nullable String> toSingleValueMap() {
 		return delegate.toSingleValueMap();
 	}
 	// endregion
@@ -110,18 +110,18 @@ public class HttpHeaders implements MultiValueMap<String, String> {
 
 	@Override
 	@Nullable
-	public List<String> get(Object key) {
+	public List<@Nullable String> get(Object key) {
 		return delegate.get(key);
 	}
 
 	@Nullable
 	@Override
-	public List<String> put(String key, List<String> value) {
+	public List<@Nullable String> put(String key, List<@Nullable String> value) {
 		return delegate.put(key, value);
 	}
 
 	@Override
-	public List<String> remove(Object key) {
+	public List<@Nullable String> remove(Object key) {
 		return delegate.remove(key);
 	}
 

src/test/java/org/springframework/data/elasticsearch/client/RestClientsTest.java

@@ -47,7 +47,6 @@ import org.springframework.data.elasticsearch.support.HttpHeaders;
 
 import com.github.tomakehurst.wiremock.WireMockServer;
 import com.github.tomakehurst.wiremock.client.WireMock;
-import com.github.tomakehurst.wiremock.common.ConsoleNotifier;
 import com.github.tomakehurst.wiremock.matching.AnythingPattern;
 import com.github.tomakehurst.wiremock.matching.EqualToPattern;
 import com.github.tomakehurst.wiremock.stubbing.StubMapping;
@@ -104,8 +103,11 @@ public class RestClientsTest {
 			defaultHeaders.add("def2", "def2-1");
 
 			AtomicInteger supplierCount = new AtomicInteger(1);
-			AtomicInteger httpClientConfigurerCount = new AtomicInteger(0);
 			AtomicInteger restClientConfigurerCount = new AtomicInteger(0);
+			AtomicInteger httpClientConfigurerCount = new AtomicInteger(0);
+			AtomicInteger connectionConfigurerCount = new AtomicInteger(0);
+			AtomicInteger connectionManagerConfigurerCount = new AtomicInteger(0);
+			AtomicInteger requestConfigurerCount = new AtomicInteger(0);
 
 			ClientConfigurationBuilder configurationBuilder = new ClientConfigurationBuilder();
 			configurationBuilder //
@@ -120,17 +122,31 @@ public class RestClientsTest {
 					});
 
 			if (clientUnderTestFactory instanceof ELCRest5ClientUnderTestFactory) {
+				configurationBuilder.withClientConfigurer(
+						Rest5Clients.ElasticsearchRest5ClientConfigurationCallback.from(rest5ClientBuilder -> {
+							restClientConfigurerCount.incrementAndGet();
+							return rest5ClientBuilder;
+						}));
 				configurationBuilder.withClientConfigurer(
 						Rest5Clients.ElasticsearchHttpClientConfigurationCallback.from(httpClientBuilder -> {
 							httpClientConfigurerCount.incrementAndGet();
 							return httpClientBuilder;
 						}));
 				configurationBuilder.withClientConfigurer(
-						Rest5Clients.ElasticsearchRest5ClientConfigurationCallback.from(rest5ClientBuilder -> {
-							restClientConfigurerCount.incrementAndGet();
-							return rest5ClientBuilder;
+						Rest5Clients.ElasticsearchConnectionConfigurationCallback.from(connectionConfigBuilder -> {
+							connectionConfigurerCount.incrementAndGet();
+							return connectionConfigBuilder;
+						}));
+				configurationBuilder.withClientConfigurer(
+						Rest5Clients.ElasticsearchConnectionManagerCallback.from(connectionManagerBuilder -> {
+							connectionManagerConfigurerCount.incrementAndGet();
+							return connectionManagerBuilder;
+						}));
+				configurationBuilder.withClientConfigurer(
+						Rest5Clients.ElasticsearchRequestConfigCallback.from(requestConfigBuilder -> {
+							requestConfigurerCount.incrementAndGet();
+							return requestConfigBuilder;
 						}));
-
 			} else if (clientUnderTestFactory instanceof ELCRestClientUnderTestFactory) {
 				configurationBuilder.withClientConfigurer(
 						RestClients.ElasticsearchHttpClientConfigurationCallback.from(httpClientBuilder -> {
@@ -177,8 +193,12 @@ public class RestClientsTest {
 				;
 			}
 
+			assertThat(restClientConfigurerCount).hasValue(clientUnderTestFactory.getExpectedRestClientConfigurerCalls());
 			assertThat(httpClientConfigurerCount).hasValue(1);
-			assertThat(restClientConfigurerCount).hasValue(clientUnderTestFactory.getExpectedRestClientConfigCalls());
+			assertThat(connectionConfigurerCount).hasValue(clientUnderTestFactory.getExpectedConnectionConfigurerCalls());
+			assertThat(connectionManagerConfigurerCount)
+					.hasValue(clientUnderTestFactory.getExpectedConnectionManagerConfigurerCalls());
+			assertThat(requestConfigurerCount).hasValue(clientUnderTestFactory.getExpectedRequestConfigurerCalls());
 		});
 	}
 
@@ -404,11 +424,23 @@ public class RestClientsTest {
 
 		protected abstract String getDisplayName();
 
-		protected Integer getExpectedRestClientConfigCalls() {
+		protected Integer getExpectedRestClientConfigurerCalls() {
 			return 0;
 		}
 
 		protected abstract int getElasticsearchMajorVersion();
+
+		public Integer getExpectedConnectionConfigurerCalls() {
+			return 0;
+		}
+
+		public Integer getExpectedConnectionManagerConfigurerCalls() {
+			return 0;
+		}
+
+		public Integer getExpectedRequestConfigurerCalls() {
+			return 0;
+		}
 	}
 
 	/**
@@ -423,7 +455,22 @@ public class RestClientsTest {
 		}
 
 		@Override
-		protected Integer getExpectedRestClientConfigCalls() {
+		protected Integer getExpectedRestClientConfigurerCalls() {
+			return 1;
+		}
+
+		@Override
+		public Integer getExpectedConnectionConfigurerCalls() {
+			return 1;
+		}
+
+		@Override
+		public Integer getExpectedConnectionManagerConfigurerCalls() {
+			return 1;
+		}
+
+		@Override
+		public Integer getExpectedRequestConfigurerCalls() {
 			return 1;
 		}
 
@@ -467,7 +514,7 @@ public class RestClientsTest {
 		}
 
 		@Override
-		protected Integer getExpectedRestClientConfigCalls() {
+		protected Integer getExpectedRestClientConfigurerCalls() {
 			return 1;
 		}
 
@@ -511,7 +558,7 @@ public class RestClientsTest {
 		}
 
 		@Override
-		protected Integer getExpectedRestClientConfigCalls() {
+		protected Integer getExpectedRestClientConfigurerCalls() {
 			return 1;
 		}
 

src/test/java/org/springframework/data/elasticsearch/config/configuration/ReactiveElasticsearchConfigurationELCTests.java

@@ -17,6 +17,7 @@ package org.springframework.data.elasticsearch.config.configuration;
 
 import static org.assertj.core.api.Assertions.*;
 
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -49,7 +50,7 @@ public class ReactiveElasticsearchConfigurationELCTests {
 	static class Config extends ReactiveElasticsearchConfiguration {
 
 		@Override
-		public ClientConfiguration clientConfiguration() {
+		public @NonNull ClientConfiguration clientConfiguration() {
 			return ClientConfiguration.builder() //
 					.connectedTo("localhost:9200") //
 					.build();

src/test/java/org/springframework/data/elasticsearch/config/nested/EnableNestedRepositoriesIntegrationTests.java

@@ -71,10 +71,10 @@ public abstract class EnableNestedRepositoriesIntegrationTests {
 		@Field(type = Text, store = true, fielddata = true) private String type;
 		@Nullable
 		@Field(type = Text, store = true, fielddata = true) private String message;
-		@Nullable private int rate;
+		private int rate;
 		@Nullable
 		@ScriptedField private Double scriptedRate;
-		@Nullable private boolean available;
+		private boolean available;
 		@Nullable private String highlightedMessage;
 		@Nullable private GeoPoint location;
 		@Nullable

src/test/java/org/springframework/data/elasticsearch/config/notnested/EnableRepositoriesIntegrationTests.java

@@ -114,10 +114,10 @@ public abstract class EnableRepositoriesIntegrationTests implements ApplicationC
 		@Field(type = Text, store = true, fielddata = true) private String type;
 		@Nullable
 		@Field(type = Text, store = true, fielddata = true) private String message;
-		@Nullable private int rate;
+		private int rate;
 		@Nullable
 		@ScriptedField private Double scriptedRate;
-		@Nullable private boolean available;
+		private boolean available;
 		@Nullable private String highlightedMessage;
 		@Nullable private GeoPoint location;
 		@Nullable
@@ -208,10 +208,10 @@ public abstract class EnableRepositoriesIntegrationTests implements ApplicationC
 		@Nullable private String type;
 		@Nullable
 		@Field(type = FieldType.Text, fielddata = true) private String message;
-		@Nullable private int rate;
+		private int rate;
 		@Nullable
 		@ScriptedField private Long scriptedRate;
-		@Nullable private boolean available;
+		private boolean available;
 		@Nullable private String highlightedMessage;
 		@Nullable private GeoPoint location;
 		@Nullable

src/test/java/org/springframework/data/elasticsearch/core/ElasticsearchIntegrationTests.java

@@ -3900,10 +3900,10 @@ public abstract class ElasticsearchIntegrationTests {
 		@Field(type = Text, store = true, fielddata = true) private String type;
 		@Nullable
 		@Field(type = Text, store = true, fielddata = true) private String message;
-		@Nullable private int rate;
+		private int rate;
 		@Nullable
 		@ScriptedField private Double scriptedRate;
-		@Nullable private boolean available;
+		private boolean available;
 		@Nullable private GeoPoint location;
 		@Nullable
 		@Version private Long version;
@@ -3918,7 +3918,7 @@ public abstract class ElasticsearchIntegrationTests {
 			@Nullable private String type;
 			@Nullable private String message;
 			@Nullable private Long version;
-			@Nullable private int rate;
+			private int rate;
 			@Nullable private GeoPoint location;
 
 			public Builder id(String id) {
@@ -4115,10 +4115,10 @@ public abstract class ElasticsearchIntegrationTests {
 		@Nullable private String type;
 		@Nullable
 		@Field(type = FieldType.Text, fielddata = true) private String message;
-		@Nullable private int rate;
+		private int rate;
 		@Nullable
 		@ScriptedField private Long scriptedRate;
-		@Nullable private boolean available;
+		private boolean available;
 		@Nullable private GeoPoint location;
 		@Nullable
 		@Version private Long version;
@@ -4806,8 +4806,7 @@ public abstract class ElasticsearchIntegrationTests {
 	@Document(indexName = "#{@indexNameProvider.indexName()}-immutable-scripted")
 	public static final class ImmutableWithScriptedEntity {
 		@Id private final String id;
-		@Field(type = Integer)
-		@Nullable private final int rate;
+		@Field(type = Integer) private final int rate;
 		@Nullable
 		@ScriptedField private final Double scriptedRate;
 
@@ -4863,9 +4862,11 @@ public abstract class ElasticsearchIntegrationTests {
 
 	@Document(indexName = "#{@indexNameProvider.indexName()}-readonly-id")
 	static class ReadonlyIdEntity {
-		@Field(type = FieldType.Keyword) private String part1;
+		@Field(type = FieldType.Keyword)
+		@Nullable private String part1;
 
-		@Field(type = FieldType.Keyword) private String part2;
+		@Field(type = FieldType.Keyword)
+		@Nullable private String part2;
 
 		@Id
 		@WriteOnlyProperty
@@ -4874,7 +4875,7 @@ public abstract class ElasticsearchIntegrationTests {
 			return part1 + '-' + part2;
 		}
 
-		public String getPart1() {
+		public @Nullable String getPart1() {
 			return part1;
 		}
 
@@ -4882,7 +4883,7 @@ public abstract class ElasticsearchIntegrationTests {
 			this.part1 = part1;
 		}
 
-		public String getPart2() {
+		public @Nullable String getPart2() {
 			return part2;
 		}
 
@@ -5006,9 +5007,11 @@ public abstract class ElasticsearchIntegrationTests {
 	private static class RootEntity {
 		@Id private String id;
 
-		@Field(type = FieldType.Object) private Child child;
+		@Field(type = FieldType.Object)
+		@Nullable private Child child;
 
-		@Field(type = FieldType.Object) private Parent parent;
+		@Field(type = FieldType.Object)
+		@Nullable private Parent parent;
 
 		@JoinTypeRelations(relations = {
 				@JoinTypeRelation(parent = "parent", children = { "child" })
@@ -5030,7 +5033,7 @@ public abstract class ElasticsearchIntegrationTests {
 			this.id = id;
 		}
 
-		public Child getChild() {
+		public @Nullable Child getChild() {
 			return child;
 		}
 
@@ -5038,7 +5041,7 @@ public abstract class ElasticsearchIntegrationTests {
 			this.child = child;
 		}
 
-		public Parent getParent() {
+		public @Nullable Parent getParent() {
 			return parent;
 		}
 

src/test/java/org/springframework/data/elasticsearch/core/EntityOperationsUnitTests.java

@@ -245,7 +245,7 @@ class EntityOperationsUnitTests {
 		@IndexedIndexName
 		@Nullable private String indexName;
 
-		public String getId() {
+		public @Nullable String getId() {
 			return id;
 		}
 

src/test/java/org/springframework/data/elasticsearch/core/LogEntityIntegrationTests.java

@@ -134,7 +134,7 @@ public abstract class LogEntityIntegrationTests {
 		@Nullable
 		@Id private String id;
 		@Nullable private String action;
-		@Nullable private long sequenceCode;
+		private long sequenceCode;
 		@Nullable
 		@Field(type = Ip) private String ip;
 		@Field(type = Date, format = DateFormat.date_time) private java.util.@Nullable Date date;
@@ -149,7 +149,7 @@ public abstract class LogEntityIntegrationTests {
 			return format;
 		}
 
-		public String getId() {
+		public @Nullable String getId() {
 			return id;
 		}
 
@@ -157,7 +157,7 @@ public abstract class LogEntityIntegrationTests {
 			this.id = id;
 		}
 
-		public String getAction() {
+		public @Nullable String getAction() {
 			return action;
 		}
 
@@ -173,7 +173,7 @@ public abstract class LogEntityIntegrationTests {
 			this.sequenceCode = sequenceCode;
 		}
 
-		public String getIp() {
+		public @Nullable String getIp() {
 			return ip;
 		}
 
@@ -181,7 +181,7 @@ public abstract class LogEntityIntegrationTests {
 			this.ip = ip;
 		}
 
-		public java.util.Date getDate() {
+		public java.util.@Nullable Date getDate() {
 			return date;
 		}
 

src/test/java/org/springframework/data/elasticsearch/core/ReactiveElasticsearchIntegrationTests.java

@@ -1298,7 +1298,7 @@ public abstract class ReactiveElasticsearchIntegrationTests {
 		@Id private String id;
 		@Nullable
 		@Field(type = Text, store = true, fielddata = true) private String message;
-		@Nullable private int rate;
+		private int rate;
 		@Nullable
 		@Version private Long version;
 
@@ -1568,9 +1568,9 @@ public abstract class ReactiveElasticsearchIntegrationTests {
 
 	@Document(indexName = "#{@indexNameProvider.indexName()}-readonly-id")
 	static class ReadonlyIdEntity {
-		@Field(type = FieldType.Keyword) private String part1;
+		@Field(type = FieldType.Keyword) private @Nullable String part1;
 
-		@Field(type = FieldType.Keyword) private String part2;
+		@Field(type = FieldType.Keyword) private @Nullable String part2;
 
 		@Id
 		@WriteOnlyProperty
@@ -1579,7 +1579,7 @@ public abstract class ReactiveElasticsearchIntegrationTests {
 			return part1 + '-' + part2;
 		}
 
-		public String getPart1() {
+		public @Nullable String getPart1() {
 			return part1;
 		}
 
@@ -1587,7 +1587,7 @@ public abstract class ReactiveElasticsearchIntegrationTests {
 			this.part1 = part1;
 		}
 
-		public String getPart2() {
+		public @Nullable String getPart2() {
 			return part2;
 		}
 

src/test/java/org/springframework/data/elasticsearch/core/aggregation/AggregationIntegrationTests.java

@@ -164,7 +164,7 @@ public abstract class AggregationIntegrationTests {
 		@Nullable
 		@Field(type = Integer, store = true) private List<Integer> publishedYears = new ArrayList<>();
 
-		@Nullable private int score;
+		private int score;
 
 		public ArticleEntity(@Nullable String id) {
 			this.id = id;

src/test/java/org/springframework/data/elasticsearch/core/convert/MappingElasticsearchConverterUnitTests.java

@@ -25,7 +25,15 @@ import java.time.LocalTime;
 import java.time.OffsetTime;
 import java.time.ZoneOffset;
 import java.time.ZonedDateTime;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
 import java.util.stream.Collectors;
 
 import org.intellij.lang.annotations.Language;
@@ -128,7 +136,7 @@ public class MappingElasticsearchConverterUnitTests {
 	public void init() {
 
 		SimpleElasticsearchMappingContext mappingContext = new SimpleElasticsearchMappingContext();
-		mappingContext.setInitialEntitySet(Collections.singleton(Rifle.class));
+		mappingContext.setInitialEntitySet(singleton(Rifle.class));
 		mappingContext.afterPropertiesSet();
 
 		mappingElasticsearchConverter = new MappingElasticsearchConverter(mappingContext, new GenericConversionService());
@@ -389,7 +397,7 @@ public class MappingElasticsearchConverterUnitTests {
 	@Test // DATAES-530
 	public void readListOfConcreteTypesCorrectly() {
 
-		sarahAsMap.put("coWorkers", Collections.singletonList(kyleAsMap));
+		sarahAsMap.put("coWorkers", singletonList(kyleAsMap));
 
 		Person target = mappingElasticsearchConverter.read(Person.class, sarahAsMap);
 
@@ -414,7 +422,7 @@ public class MappingElasticsearchConverterUnitTests {
 
 		Map<String, Object> target = writeToMap(sarahConnor);
 		assertThat(target.get("shippingAddresses")).isInstanceOf(Map.class);
-		assertThat(target.get("shippingAddresses")).isEqualTo(Collections.singletonMap("home", gratiotAveAsMap));
+		assertThat(target.get("shippingAddresses")).isEqualTo(singletonMap("home", gratiotAveAsMap));
 	}
 
 	@Test // DATAES-530
@@ -433,7 +441,7 @@ public class MappingElasticsearchConverterUnitTests {
 	@Test // DATAES-530
 	public void readConcreteMapCorrectly() {
 
-		sarahAsMap.put("shippingAddresses", Collections.singletonMap("home", gratiotAveAsMap));
+		sarahAsMap.put("shippingAddresses", singletonMap("home", gratiotAveAsMap));
 
 		Person target = mappingElasticsearchConverter.read(Person.class, sarahAsMap);
 
@@ -443,7 +451,7 @@ public class MappingElasticsearchConverterUnitTests {
 	@Test // DATAES-530
 	public void readInterfaceMapCorrectly() {
 
-		sarahAsMap.put("inventoryMap", Collections.singletonMap("glock19", gunAsMap));
+		sarahAsMap.put("inventoryMap", singletonMap("glock19", gunAsMap));
 
 		Person target = mappingElasticsearchConverter.read(Person.class, sarahAsMap);
 
@@ -490,7 +498,7 @@ public class MappingElasticsearchConverterUnitTests {
 	public void readGenericListList() {
 
 		Document source = Document.create();
-		source.put("objectList", Collections.singletonList(Arrays.asList(t800AsMap, gunAsMap)));
+		source.put("objectList", singletonList(Arrays.asList(t800AsMap, gunAsMap)));
 
 		Skynet target = mappingElasticsearchConverter.read(Skynet.class, source);
 
@@ -515,7 +523,7 @@ public class MappingElasticsearchConverterUnitTests {
 	public void readGenericMap() {
 
 		Document source = Document.create();
-		source.put("objectMap", Collections.singletonMap("glock19", gunAsMap));
+		source.put("objectMap", singletonMap("glock19", gunAsMap));
 
 		Skynet target = mappingElasticsearchConverter.read(Skynet.class, source);
 
@@ -527,23 +535,23 @@ public class MappingElasticsearchConverterUnitTests {
 
 		Skynet skynet = new Skynet();
 		skynet.objectMap = new LinkedHashMap<>();
-		skynet.objectMap.put("inventory", Collections.singletonMap("glock19", gun));
+		skynet.objectMap.put("inventory", singletonMap("glock19", gun));
 
 		Map<String, Object> target = writeToMap(skynet);
 
 		assertThat((Map<String, Object>) target.get("objectMap")).containsEntry("inventory",
-				Collections.singletonMap("glock19", gunAsMap));
+				singletonMap("glock19", gunAsMap));
 	}
 
 	@Test // DATAES-530
 	public void readGenericMapMap() {
 
 		Document source = Document.create();
-		source.put("objectMap", Collections.singletonMap("inventory", Collections.singletonMap("glock19", gunAsMap)));
+		source.put("objectMap", singletonMap("inventory", singletonMap("glock19", gunAsMap)));
 
 		Skynet target = mappingElasticsearchConverter.read(Skynet.class, source);
 
-		assertThat(target.getObjectMap()).containsEntry("inventory", Collections.singletonMap("glock19", gun));
+		assertThat(target.getObjectMap()).containsEntry("inventory", singletonMap("glock19", gun));
 	}
 
 	@Test // DATAES-530
@@ -575,7 +583,7 @@ public class MappingElasticsearchConverterUnitTests {
 	@Test // DATAES-530
 	public void writesNestedAliased() {
 
-		t800.inventoryList = Collections.singletonList(rifle);
+		t800.inventoryList = singletonList(rifle);
 		Map<String, Object> target = writeToMap(t800);
 
 		assertThat((List<Document>) target.get("inventoryList")).contains(rifleAsMap);
@@ -589,7 +597,7 @@ public class MappingElasticsearchConverterUnitTests {
 	@Test // DATAES-530
 	public void readsNestedAliased() {
 
-		t800AsMap.put("inventoryList", Collections.singletonList(rifleAsMap));
+		t800AsMap.put("inventoryList", singletonList(rifleAsMap));
 
 		assertThat(mappingElasticsearchConverter.read(Person.class, t800AsMap).getInventoryList()).containsExactly(rifle);
 	}
@@ -911,12 +919,12 @@ public class MappingElasticsearchConverterUnitTests {
 	void shouldWriteMapContainingCollectionContainingMap() throws JSONException {
 
 		class EntityWithMapCollectionMap {
-			Map<String, Object> map;
+			Map<String, Object> map = Map.of();
 		}
 		class InnerEntity {
-			String prop1;
+			@Nullable String prop1;
 
-			String prop2;
+			@Nullable String prop2;
 
 			public InnerEntity() {}
 
@@ -928,8 +936,8 @@ public class MappingElasticsearchConverterUnitTests {
 		}
 
 		var entity = new EntityWithMapCollectionMap();
-		entity.map = Collections.singletonMap("collection",
-				Collections.singletonList(Collections.singletonMap("destination", new InnerEntity("prop1", "prop2"))));
+		entity.map = singletonMap("collection",
+				singletonList(singletonMap("destination", new InnerEntity("prop1", "prop2"))));
 
 		var expected = """
 				{
@@ -1069,67 +1077,79 @@ public class MappingElasticsearchConverterUnitTests {
 		class RangeEntity {
 
 			@Id private String id;
-			@Field(type = FieldType.Integer_Range) private Range<Integer> integerRange;
-			@Field(type = FieldType.Float_Range) private Range<Float> floatRange;
-			@Field(type = FieldType.Long_Range) private Range<Long> longRange;
-			@Field(type = FieldType.Double_Range) private Range<Double> doubleRange;
-			@Field(type = FieldType.Date_Range) private Range<Date> dateRange;
-			@Field(type = FieldType.Date_Range, format = DateFormat.year_month_day) private Range<LocalDate> localDateRange;
+			@Field(type = FieldType.Integer_Range)
+			@Nullable private Range<Integer> integerRange;
+			@Field(type = FieldType.Float_Range)
+			@Nullable private Range<Float> floatRange;
+			@Field(type = FieldType.Long_Range)
+			@Nullable private Range<Long> longRange;
+			@Field(type = FieldType.Double_Range)
+			@Nullable private Range<Double> doubleRange;
+			@Field(type = FieldType.Date_Range)
+			@Nullable private Range<Date> dateRange;
+			@Field(type = FieldType.Date_Range, format = DateFormat.year_month_day)
+			@Nullable private Range<LocalDate> localDateRange;
 			@Field(type = FieldType.Date_Range,
-					format = DateFormat.hour_minute_second_millis) private Range<LocalTime> localTimeRange;
+					format = DateFormat.hour_minute_second_millis)
+			@Nullable private Range<LocalTime> localTimeRange;
 			@Field(type = FieldType.Date_Range,
-					format = DateFormat.date_hour_minute_second_millis) private Range<LocalDateTime> localDateTimeRange;
-			@Field(type = FieldType.Date_Range, format = DateFormat.time) private Range<OffsetTime> offsetTimeRange;
-			@Field(type = FieldType.Date_Range) private Range<ZonedDateTime> zonedDateTimeRange;
-			@Field(type = FieldType.Date_Range, storeNullValue = true) private Range<ZonedDateTime> nullRange;
+					format = DateFormat.date_hour_minute_second_millis)
+			@Nullable private Range<LocalDateTime> localDateTimeRange;
+			@Field(type = FieldType.Date_Range, format = DateFormat.time)
+			@Nullable private Range<OffsetTime> offsetTimeRange;
+			@Field(type = FieldType.Date_Range)
+			@Nullable private Range<ZonedDateTime> zonedDateTimeRange;
+			@Field(type = FieldType.Date_Range, storeNullValue = true)
+			@Nullable private Range<ZonedDateTime> nullRange;
 
-			@Field(type = FieldType.Integer_Range) private List<Range<Integer>> integerRangeList;
+			@Field(type = FieldType.Integer_Range)
+			@Nullable private List<Range<Integer>> integerRangeList;
 
 			public String getId() {
 				return id;
 			}
 
-			public Range<Integer> getIntegerRange() {
+			public @Nullable Range<Integer> getIntegerRange() {
 				return integerRange;
 			}
 
-			public Range<Float> getFloatRange() {
+			public @Nullable Range<Float> getFloatRange() {
 				return floatRange;
 			}
 
-			public Range<Long> getLongRange() {
+			public @Nullable Range<Long> getLongRange() {
 				return longRange;
 			}
 
-			public Range<Double> getDoubleRange() {
+			public @Nullable Range<Double> getDoubleRange() {
 				return doubleRange;
 			}
 
-			public Range<Date> getDateRange() {
+			public @Nullable Range<Date> getDateRange() {
 				return dateRange;
 			}
 
-			public Range<LocalDate> getLocalDateRange() {
+			public @Nullable Range<LocalDate> getLocalDateRange() {
 				return localDateRange;
 			}
 
-			public Range<LocalTime> getLocalTimeRange() {
+			public @Nullable Range<LocalTime> getLocalTimeRange() {
 				return localTimeRange;
 			}
 
-			public Range<LocalDateTime> getLocalDateTimeRange() {
+			public @Nullable Range<LocalDateTime> getLocalDateTimeRange() {
 				return localDateTimeRange;
 			}
 
-			public Range<OffsetTime> getOffsetTimeRange() {
+			public @Nullable Range<OffsetTime> getOffsetTimeRange() {
 				return offsetTimeRange;
 			}
 
-			public Range<ZonedDateTime> getZonedDateTimeRange() {
+			public @Nullable Range<ZonedDateTime> getZonedDateTimeRange() {
 				return zonedDateTimeRange;
 			}
 
-			public Range<ZonedDateTime> getNullRange() {
+			public @Nullable Range<ZonedDateTime> getNullRange() {
 				return nullRange;
 			}
 
@@ -1181,7 +1201,7 @@ public class MappingElasticsearchConverterUnitTests {
 				this.nullRange = nullRange;
 			}
 
-			public List<Range<Integer>> getIntegerRangeList() {
+			public @Nullable List<Range<Integer>> getIntegerRangeList() {
 				return integerRangeList;
 			}
 
@@ -2639,8 +2659,7 @@ public class MappingElasticsearchConverterUnitTests {
 		@Nullable private GeoPoint pointB;
 		@Nullable
 		@GeoPointField private String pointC;
-		@Nullable
-		@GeoPointField private double[] pointD;
+		@GeoPointField private double @Nullable [] pointD;
 
 		@Nullable
 		public String getId() {
@@ -2705,12 +2724,11 @@ public class MappingElasticsearchConverterUnitTests {
 			this.pointC = pointC;
 		}
 
-		@Nullable
-		public double[] getPointD() {
+		public double @Nullable [] getPointD() {
 			return pointD;
 		}
 
-		public void setPointD(@Nullable double[] pointD) {
+		public void setPointD(double @Nullable [] pointD) {
 			this.pointD = pointD;
 		}
 	}
@@ -3259,7 +3277,8 @@ public class MappingElasticsearchConverterUnitTests {
 		@Id
 		@Nullable private String id;
 
-		@Field(type = FieldType.Nested, name = "level-one") private List<Level1> level1Entries;
+		@Field(type = FieldType.Nested, name = "level-one")
+		@Nullable private List<Level1> level1Entries;
 
 		@Nullable
 		public String getId() {
@@ -3270,7 +3289,7 @@ public class MappingElasticsearchConverterUnitTests {
 			this.id = id;
 		}
 
-		public List<Level1> getLevel1Entries() {
+		public @Nullable List<Level1> getLevel1Entries() {
 			return level1Entries;
 		}
 
@@ -3279,9 +3298,10 @@ public class MappingElasticsearchConverterUnitTests {
 		}
 
 		static class Level1 {
-			@Field(type = FieldType.Nested, name = "level-two") private List<Level2> level2Entries;
+			@Field(type = FieldType.Nested, name = "level-two")
+			@Nullable private List<Level2> level2Entries;
 
-			public List<Level2> getLevel2Entries() {
+			public @Nullable List<Level2> getLevel2Entries() {
 				return level2Entries;
 			}
 
@@ -3291,9 +3311,10 @@ public class MappingElasticsearchConverterUnitTests {
 		}
 
 		static class Level2 {
-			@Field(type = FieldType.Keyword, name = "key-word") private String keyWord;
+			@Field(type = FieldType.Keyword, name = "key-word")
+			@Nullable private String keyWord;
 
-			public String getKeyWord() {
+			public @Nullable String getKeyWord() {
 				return keyWord;
 			}
 

src/test/java/org/springframework/data/elasticsearch/core/geo/GeoIntegrationTests.java

@@ -424,12 +424,11 @@ public abstract class GeoIntegrationTests {
 		@Nullable private String name;
 		@Nullable
 		@GeoPointField private String locationAsString;
-		@Nullable
-		@GeoPointField private double[] locationAsArray;
+		@GeoPointField private double @Nullable [] locationAsArray;
 		@Nullable
 		@GeoPointField private String locationAsGeoHash;
 
-		public String getId() {
+		public @Nullable String getId() {
 			return id;
 		}
 
@@ -437,7 +436,7 @@ public abstract class GeoIntegrationTests {
 			this.id = id;
 		}
 
-		public String getName() {
+		public @Nullable String getName() {
 			return name;
 		}
 
@@ -445,7 +444,7 @@ public abstract class GeoIntegrationTests {
 			this.name = name;
 		}
 
-		public String getLocationAsString() {
+		public @Nullable String getLocationAsString() {
 			return locationAsString;
 		}
 
@@ -461,7 +460,7 @@ public abstract class GeoIntegrationTests {
 			this.locationAsArray = locationAsArray;
 		}
 
-		public String getLocationAsGeoHash() {
+		public @Nullable String getLocationAsGeoHash() {
 			return locationAsGeoHash;
 		}
 

src/test/java/org/springframework/data/elasticsearch/core/index/MappingBuilderIntegrationTests.java

@@ -724,8 +724,7 @@ public abstract class MappingBuilderIntegrationTests extends MappingContextBaseT
 	static class DenseVectorEntity {
 		@Nullable
 		@Id private String id;
-		@Nullable
-		@Field(type = Dense_Vector, dims = 3) private float[] dense_vector;
+		@Field(type = Dense_Vector, dims = 3) private float @Nullable [] dense_vector;
 
 		@Nullable
 		public String getId() {
@@ -736,12 +735,11 @@ public abstract class MappingBuilderIntegrationTests extends MappingContextBaseT
 			this.id = id;
 		}
 
-		@Nullable
-		public float[] getDense_vector() {
+		public float @Nullable [] getDense_vector() {
 			return dense_vector;
 		}
 
-		public void setDense_vector(@Nullable float[] dense_vector) {
+		public void setDense_vector(float @Nullable [] dense_vector) {
 			this.dense_vector = dense_vector;
 		}
 	}
@@ -915,7 +913,8 @@ public abstract class MappingBuilderIntegrationTests extends MappingContextBaseT
 		@Nullable
 		@Id private String id;
 
-		@Field(type = FieldType.Dense_Vector, dims = 42, knnSimilarity = KnnSimilarity.COSINE) private double[] denseVector;
+		@Field(type = FieldType.Dense_Vector, dims = 42,
+				knnSimilarity = KnnSimilarity.COSINE) private double @Nullable [] denseVector;
 	}
 
 	@Mapping(aliases = {

src/test/java/org/springframework/data/elasticsearch/core/index/MappingBuilderUnitTests.java

@@ -1398,7 +1398,7 @@ public class MappingBuilderUnitTests extends MappingContextBaseTests {
 
 			@Field("mapping-property")
 			@Mapping(mappingPath = "/mappings/test-field-analyzed-mappings.json") //
-			@Nullable private byte[] mappingProperty;
+			private byte @Nullable [] mappingProperty;
 		}
 
 		@SuppressWarnings("unused")
@@ -1820,8 +1820,7 @@ public class MappingBuilderUnitTests extends MappingContextBaseTests {
 		@Nullable private GeoPoint pointB;
 		@Nullable
 		@GeoPointField private String pointC;
-		@Nullable
-		@GeoPointField private double[] pointD;
+		@GeoPointField private double @Nullable [] pointD;
 
 		@Nullable
 		@GeoShapeField private String shape1;
@@ -1892,12 +1891,11 @@ public class MappingBuilderUnitTests extends MappingContextBaseTests {
 			this.pointC = pointC;
 		}
 
-		@Nullable
-		public double[] getPointD() {
+		public double @Nullable [] getPointD() {
 			return pointD;
 		}
 
-		public void setPointD(@Nullable double[] pointD) {
+		public void setPointD(double @Nullable [] pointD) {
 			this.pointD = pointD;
 		}
 
@@ -2171,8 +2169,7 @@ public class MappingBuilderUnitTests extends MappingContextBaseTests {
 	static class DenseVectorEntity {
 		@Nullable
 		@Id private String id;
-		@Nullable
-		@Field(type = FieldType.Dense_Vector, dims = 16) private float[] my_vector;
+		@Field(type = FieldType.Dense_Vector, dims = 16) private float @Nullable [] my_vector;
 
 		@Nullable
 		public String getId() {
@@ -2183,12 +2180,11 @@ public class MappingBuilderUnitTests extends MappingContextBaseTests {
 			this.id = id;
 		}
 
-		@Nullable
-		public float[] getMy_vector() {
+		public float @Nullable [] getMy_vector() {
 			return my_vector;
 		}
 
-		public void setMy_vector(@Nullable float[] my_vector) {
+		public void setMy_vector(float @Nullable [] my_vector) {
 			this.my_vector = my_vector;
 		}
 	}
@@ -2198,10 +2194,9 @@ public class MappingBuilderUnitTests extends MappingContextBaseTests {
 		@Nullable
 		@Id private String id;
 
-		@Nullable
 		@Field(type = FieldType.Dense_Vector, dims = 16, elementType = FieldElementType.FLOAT,
 				knnIndexOptions = @KnnIndexOptions(type = KnnAlgorithmType.HNSW, m = 16, efConstruction = 100),
-				knnSimilarity = KnnSimilarity.DOT_PRODUCT) private float[] my_vector;
+				knnSimilarity = KnnSimilarity.DOT_PRODUCT) private float @Nullable [] my_vector;
 
 		@Nullable
 		public String getId() {
@@ -2212,12 +2207,11 @@ public class MappingBuilderUnitTests extends MappingContextBaseTests {
 			this.id = id;
 		}
 
-		@Nullable
-		public float[] getMy_vector() {
+		public float @Nullable [] getMy_vector() {
 			return my_vector;
 		}
 
-		public void setMy_vector(@Nullable float[] my_vector) {
+		public void setMy_vector(float @Nullable [] my_vector) {
 			this.my_vector = my_vector;
 		}
 	}
@@ -2277,7 +2271,7 @@ public class MappingBuilderUnitTests extends MappingContextBaseTests {
 	static class DenseVectorMisMatchConfidenceIntervalClass {
 		@Field(type = Dense_Vector, dims = 16, elementType = FieldElementType.FLOAT,
 				knnIndexOptions = @KnnIndexOptions(type = KnnAlgorithmType.HNSW, m = 16, confidenceInterval = 0.95F),
-				knnSimilarity = KnnSimilarity.DOT_PRODUCT) private float[] dense_vector;
+				knnSimilarity = KnnSimilarity.DOT_PRODUCT) private float @Nullable [] dense_vector;
 	}
 
 	static class DisabledMappingProperty {

src/test/java/org/springframework/data/elasticsearch/core/index/MappingParametersTest.java

@@ -110,10 +110,10 @@ public class MappingParametersTest extends MappingContextBaseTests {
 	}
 
 	static class DenseVectorInvalidDimsClass {
-		@Field(type = Dense_Vector, dims = 4097) private float[] dense_vector;
+		@Field(type = Dense_Vector, dims = 4097) private float @Nullable [] dense_vector;
 	}
 
 	static class DenseVectorMissingDimsClass {
-		@Field(type = Dense_Vector) private float[] dense_vector;
+		@Field(type = Dense_Vector) private float @Nullable [] dense_vector;
 	}
 }

src/test/java/org/springframework/data/elasticsearch/core/index/ReactiveIndexOperationsIntegrationTests.java

@@ -444,7 +444,8 @@ public abstract class ReactiveIndexOperationsIntegrationTests {
 	})
 	private static class EntityWithAliases {
 		@Nullable private @Id String id;
-		@Field(type = Text) private String type;
+		@Field(type = Text)
+		@Nullable private String type;
 
 		@Nullable
 		public String getId() {
@@ -455,7 +456,7 @@ public abstract class ReactiveIndexOperationsIntegrationTests {
 			this.id = id;
 		}
 
-		public String getType() {
+		public @Nullable String getType() {
 			return type;
 		}
 

src/test/java/org/springframework/data/elasticsearch/core/mapping/SimpleElasticsearchPersistentPropertyUnitTests.java

@@ -325,7 +325,7 @@ public class SimpleElasticsearchPersistentPropertyUnitTests {
 
 	static class FieldNamingStrategyEntity {
 		@Nullable private String withoutCustomFieldName;
-		@Field(name = "CUStomFIEldnAME") private String withCustomFieldName;
+		@Field(name = "CUStomFIEldnAME")  @Nullable private String withCustomFieldName;
 
 		@Nullable
 		public String getWithoutCustomFieldName() {
@@ -336,7 +336,7 @@ public class SimpleElasticsearchPersistentPropertyUnitTests {
 			this.withoutCustomFieldName = withoutCustomFieldName;
 		}
 
-		public String getWithCustomFieldName() {
+		public @Nullable String getWithCustomFieldName() {
 			return withCustomFieldName;
 		}
 

src/test/java/org/springframework/data/elasticsearch/core/query/CriteriaQueryIntegrationTests.java

@@ -715,7 +715,7 @@ public abstract class CriteriaQueryIntegrationTests {
 		@Field(type = Text, store = true, fielddata = true) private String type;
 		@Nullable
 		@Field(type = Text, store = true, fielddata = true) private String message;
-		@Nullable private int rate;
+		private int rate;
 		@Nullable
 		@Version private Long version;
 

src/test/java/org/springframework/data/elasticsearch/junit/jupiter/ClusterConnection.java

@@ -27,7 +27,6 @@ import java.util.Properties;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.jspecify.annotations.Nullable;
-import org.junit.jupiter.api.extension.ExtensionContext;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.testcontainers.elasticsearch.ElasticsearchContainer;
@@ -41,7 +40,7 @@ import org.testcontainers.utility.DockerImageName;
  *
  * @author Peter-Josef Meisch
  */
-public class ClusterConnection implements ExtensionContext.Store.CloseableResource {
+public class ClusterConnection implements AutoCloseable {
 
 	private static final Log LOGGER = LogFactory.getLog(ClusterConnection.class);
 
@@ -106,7 +105,7 @@ public class ClusterConnection implements ExtensionContext.Store.CloseableResour
 				LOGGER.warn("DATAES_ELASTICSEARCH_PORT does not contain a number");
 			}
 
-			return ClusterConnectionInfo.builder().withIntegrationtestEnvironment(IntegrationtestEnvironment.get())
+			return ClusterConnectionInfo.builder(IntegrationtestEnvironment.get())
 					.withHostAndPort(host, port).build();
 		}
 
@@ -138,11 +137,10 @@ public class ClusterConnection implements ExtensionContext.Store.CloseableResour
 					.withEnv(testcontainersProperties).withStartupTimeout(Duration.ofMinutes(2)).withReuse(true);
 			elasticsearchContainer.start();
 
-			return ClusterConnectionInfo.builder() //
-					.withIntegrationtestEnvironment(integrationtestEnvironment)
+			return ClusterConnectionInfo.builder(integrationtestEnvironment)
 					.withHostAndPort(elasticsearchContainer.getHost(),
-							elasticsearchContainer.getMappedPort(ELASTICSEARCH_DEFAULT_PORT)) //
-					.withElasticsearchContainer(elasticsearchContainer) //
+							elasticsearchContainer.getMappedPort(ELASTICSEARCH_DEFAULT_PORT))
+					.withElasticsearchContainer(elasticsearchContainer)
 					.build();
 		} catch (Exception e) {
 			LOGGER.error("Could not start Elasticsearch container", e);

src/test/java/org/springframework/data/elasticsearch/junit/jupiter/ClusterConnectionInfo.java

@@ -24,7 +24,7 @@ import org.testcontainers.elasticsearch.ElasticsearchContainer;
  * The {@link #host}, {@link #httpPort} and {@link #useSsl} values specify the values needed to connect to the cluster
  * with a rest client for both a local started cluster and for one defined by the cluster URL when creating the
  * {@link ClusterConnection}.<br/>
- * The object must be created by using a {@link ClusterConnectionInfo.Builder}.
+ * The object must be created by using a {@link Builder}.
  *
  * @author Peter-Josef Meisch
  */
@@ -36,8 +36,8 @@ public final class ClusterConnectionInfo {
 	private final String clusterName;
 	@Nullable private final ElasticsearchContainer elasticsearchContainer;
 
-	public static Builder builder() {
-		return new Builder();
+	public static Builder builder(IntegrationtestEnvironment integrationtestEnvironment) {
+		return new Builder(integrationtestEnvironment);
 	}
 
 	private ClusterConnectionInfo(IntegrationtestEnvironment integrationtestEnvironment, String host, int httpPort,
@@ -84,13 +84,12 @@ public final class ClusterConnectionInfo {
 	public static class Builder {
 		private IntegrationtestEnvironment integrationtestEnvironment;
 		private boolean useSsl = false;
-		private String host;
+		private String host = "";
 		private int httpPort;
 		@Nullable private ElasticsearchContainer elasticsearchContainer;
 
-		public Builder withIntegrationtestEnvironment(IntegrationtestEnvironment integrationtestEnvironment) {
+		public Builder(IntegrationtestEnvironment integrationtestEnvironment) {
 			this.integrationtestEnvironment = integrationtestEnvironment;
-			return this;
 		}
 
 		public Builder withHostAndPort(String host, int httpPort) {

src/test/java/org/springframework/data/elasticsearch/repositories/cdi/CdiRepositoryTests.java

@@ -176,7 +176,7 @@ public class CdiRepositoryTests {
 		@Nullable
 		@Field(type = FieldType.Float) private Float price;
 		@Nullable private Integer popularity;
-		@Nullable private boolean available;
+		private boolean available;
 		@Nullable private String location;
 		@Nullable private Date lastModified;
 
@@ -293,11 +293,12 @@ public class CdiRepositoryTests {
 
 		@Id private String id;
 
-		private String name;
+		@Nullable private String name;
 
-		@Field(type = FieldType.Nested) private List<Car> car;
+		@Field(type = FieldType.Nested)
+		@Nullable private List<Car> car;
 
-		@Field(type = FieldType.Nested, includeInParent = true) private List<Book> books;
+		@Field(type = FieldType.Nested, includeInParent = true) private @Nullable List<Book> books;
 
 	}
 

src/test/java/org/springframework/data/elasticsearch/repositories/custommethod/CustomMethodRepositoryIntegrationTests.java

@@ -2443,8 +2443,8 @@ public abstract class CustomMethodRepositoryIntegrationTests {
 		@Field(type = Text, store = true, fielddata = true) private String message;
 		@Nullable
 		@Field(type = Keyword) private String keyword;
-		@Nullable private int rate;
-		@Nullable private boolean available;
+		private int rate;
+		private boolean available;
 		@Nullable private GeoPoint location;
 		@Nullable
 		@Version private Long version;

src/test/java/org/springframework/data/elasticsearch/repositories/geo/GeoRepositoryIntegrationTests.java

@@ -116,8 +116,7 @@ public abstract class GeoRepositoryIntegrationTests {
 		@Nullable private GeoPoint pointB;
 		@Nullable
 		@GeoPointField private String pointC;
-		@Nullable
-		@GeoPointField private double[] pointD;
+		@GeoPointField private double @Nullable [] pointD;
 
 		@Nullable
 		public String getId() {
@@ -182,12 +181,11 @@ public abstract class GeoRepositoryIntegrationTests {
 			this.pointC = pointC;
 		}
 
-		@Nullable
-		public double[] getPointD() {
+		public double @Nullable [] getPointD() {
 			return pointD;
 		}
 
-		public void setPointD(@Nullable double[] pointD) {
+		public void setPointD(double @Nullable [] pointD) {
 			this.pointD = pointD;
 		}
 	}

src/test/java/org/springframework/data/elasticsearch/repositories/knn/KnnSearchIntegrationTests.java

@@ -165,12 +165,11 @@ public abstract class KnnSearchIntegrationTests {
 			this.message = message;
 		}
 
-		@Nullable
-		public float[] getVector() {
+		public float @Nullable [] getVector() {
 			return vector;
 		}
 
-		public void setVector(@Nullable float[] vector) {
+		public void setVector(float @Nullable [] vector) {
 			this.vector = vector;
 		}
 	}

src/test/java/org/springframework/data/elasticsearch/repository/query/RepositoryStringQueryUnitTests.java

@@ -510,7 +510,7 @@ public class RepositoryStringQueryUnitTests extends RepositoryStringQueryUnitTes
 	@Document(indexName = "test-index-person-query-unittest")
 	static class Person {
 
-		@Nullable public int age;
+		public int age;
 		@Nullable
 		@Id private String id;
 		@Nullable private String name;
@@ -519,7 +519,6 @@ public class RepositoryStringQueryUnitTests extends RepositoryStringQueryUnitTes
 		@Nullable
 		@Field(type = FieldType.Nested, includeInParent = true) private List<Book> books;
 
-		@Nullable
 		public int getAge() {
 			return age;
 		}

src/test/java/org/springframework/data/elasticsearch/repository/query/keywords/QueryKeywordsIntegrationTests.java

@@ -296,7 +296,7 @@ abstract class QueryKeywordsIntegrationTests {
 		@Field(type = FieldType.Keyword) private String text;
 		@Nullable
 		@Field(type = FieldType.Float) private Float price;
-		@Nullable private boolean available;
+		private boolean available;
 		@Nullable
 		@Field(name = "sort-name", type = FieldType.Keyword) private String sortName;
 

src/test/java/org/springframework/data/elasticsearch/repository/query/valueconverter/ReactiveValueConverterIntegrationTests.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.elasticsearch.repository.query.valueconverter;
 
+import org.jspecify.annotations.NonNull;
 import reactor.core.publisher.Flux;
 import reactor.test.StepVerifier;
 
@@ -125,12 +126,12 @@ public abstract class ReactiveValueConverterIntegrationTests {
 		public static final String PREFIX = "text-";
 
 		@Override
-		public Object write(Object value) {
+		public @NonNull Object write(@NonNull Object value) {
 			return PREFIX + value.toString();
 		}
 
 		@Override
-		public Object read(Object value) {
+		public @NonNull Object read(@NonNull Object value) {
 
 			String valueString = value.toString();
 

src/test/java/org/springframework/data/elasticsearch/repository/query/valueconverter/ValueConverterIntegrationTests.java

@@ -17,6 +17,7 @@ package org.springframework.data.elasticsearch.repository.query.valueconverter;
 
 import static org.assertj.core.api.Assertions.*;
 
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.DisplayName;
@@ -121,12 +122,12 @@ abstract class ValueConverterIntegrationTests {
 		public static final String PREFIX = "text-";
 
 		@Override
-		public Object write(Object value) {
+		public Object write(@NonNull Object value) {
 			return PREFIX + value.toString();
 		}
 
 		@Override
-		public Object read(Object value) {
+		public Object read(@NonNull Object value) {
 
 			String valueString = value.toString();
 

src/test/java/org/springframework/data/elasticsearch/repository/support/ElasticsearchRepositoryIntegrationTests.java

@@ -664,8 +664,8 @@ abstract class ElasticsearchRepositoryIntegrationTests {
 		@Field(type = FieldType.Text, store = true, fielddata = true) private String type;
 		@Nullable
 		@Field(type = FieldType.Text, store = true, fielddata = true) private String message;
-		@Nullable private int rate;
-		@Nullable private boolean available;
+		private int rate;
+		private boolean available;
 		@Nullable
 		@Version private Long version;
 

src/test/resources/testcontainers-elasticsearch.properties

@@ -15,7 +15,7 @@
 #
 #
 sde.testcontainers.image-name=docker.elastic.co/elasticsearch/elasticsearch
-sde.testcontainers.image-version=9.0.3
+sde.testcontainers.image-version=9.0.4
 #
 #
 # needed as we do a DELETE /* at the end of the tests, will be required from 8.0 on, produces a warning since 7.13