Upgrade the build to Java 25

See gh-35531
Closes gh-35530

.github/actions/build/action.yml

@@ -19,7 +19,7 @@ inputs:
   java-version:
     description: 'Java version to compile and test with'
     required: false
-    default: '24'
+    default: '25'
   publish:
     description: 'Whether to publish artifacts ready for deployment to Artifactory'
     required: false

.github/actions/prepare-gradle-build/action.yml

@@ -19,7 +19,7 @@ inputs:
   java-version:
     description: 'Java version to use for the build'
     required: false
-    default: '24'
+    default: '25'
 runs:
   using: composite
   steps:
@@ -30,7 +30,7 @@ runs:
         java-version: |
           ${{ inputs.java-early-access == 'true' && format('{0}-ea', inputs.java-version) || inputs.java-version }}
           ${{ inputs.java-toolchain == 'true' && '17' || '' }}
-          24
+          25
     - name: Set Up Gradle
       uses: gradle/actions/setup-gradle@ac638b010cf58a27ee6c972d7336334ccaf61c96 # v4.4.1
       with:

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ jobs:
             toolchain: false
           - version: 21
             toolchain: true
-          - version: 24
+          - version: 25
             toolchain: true
         exclude:
           - os:

.sdkmanrc

@@ -1,3 +1,3 @@
 # Enable auto-env through the sdkman_auto_env config
 # Add key=value pairs of SDKs to use below
-java=24.0.2-librca
+java=25-librca

buildSrc/src/main/java/org/springframework/build/JavaConventions.java

@@ -45,7 +45,7 @@ public class JavaConventions {
 	 * <p>NOTE: If you update this value, you should also update the value used in
 	 * the {@code javadoc} task in {@code framework-api.gradle}.
 	 */
-	private static final JavaLanguageVersion DEFAULT_LANGUAGE_VERSION = JavaLanguageVersion.of(24);
+	private static final JavaLanguageVersion DEFAULT_LANGUAGE_VERSION = JavaLanguageVersion.of(25);
 
 	/**
 	 * The Java version we should use as the baseline for the compiled bytecode

framework-api/framework-api.gradle

@@ -22,7 +22,7 @@ dependencies {
 
 javadoc {
 	javadocTool.set(javaToolchains.javadocToolFor({
-		languageVersion = JavaLanguageVersion.of(24)
+		languageVersion = JavaLanguageVersion.of(25)
 	}))
 
 	title = "${rootProject.description} ${version} API"

framework-docs/framework-docs.gradle

@@ -1,3 +1,4 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompilationTask
 
 plugins {
@@ -43,10 +44,14 @@ repositories {
 	}
 }
 
-// To avoid a redeclaration error with Kotlin compiler
-tasks.named('compileKotlin', KotlinCompilationTask.class) {
+// To avoid a redeclaration error with Kotlin compiler and set the JVM target
+tasks.withType(KotlinCompilationTask.class).configureEach {
 	javaSources.from = []
-	compilerOptions.freeCompilerArgs = [ "-Xannotation-default-target=param-property" ] // Upcoming default, see https://youtrack.jetbrains.com/issue/KT-73255
+	compilerOptions.jvmTarget = JvmTarget.JVM_17
+	compilerOptions.freeCompilerArgs.addAll(
+			"-Xjdk-release=17", // Needed due to https://youtrack.jetbrains.com/issue/KT-49746
+			"-Xannotation-default-target=param-property" // Upcoming default, see https://youtrack.jetbrains.com/issue/KT-73255
+	)
 }
 
 dependencies {

gradle/spring-module.gradle

@@ -78,7 +78,7 @@ javadoc {
 		// Change modularity mismatch from warn to info.
 		// See https://github.com/spring-projects/spring-framework/issues/27497
 		addStringOption("-link-modularity-mismatch", "info")
-		// With the javadoc tool on Java 24, it appears that the 'reference'
+		// With the javadoc tool on Java 25, it appears that the 'reference'
 		// group is always active and the '-reference' flag is not honored.
 		// Thus, we do NOT fail the build on Javadoc warnings due to
 		// cross-module @see and @link references which are only reachable

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/MultipartWebClientIntegrationTests.java

@@ -25,6 +25,7 @@ import java.util.stream.Collectors;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import org.junit.jupiter.api.condition.JRE;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.core.scheduler.Schedulers;
@@ -60,8 +61,10 @@ import org.springframework.web.reactive.function.client.WebClient;
 import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
 import org.springframework.web.testfixture.http.server.reactive.bootstrap.AbstractHttpHandlerIntegrationTests;
 import org.springframework.web.testfixture.http.server.reactive.bootstrap.HttpServer;
+import org.springframework.web.testfixture.http.server.reactive.bootstrap.JettyHttpServer;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assumptions.assumeThat;
 
 class MultipartWebClientIntegrationTests extends AbstractHttpHandlerIntegrationTests {
 
@@ -166,6 +169,11 @@ class MultipartWebClientIntegrationTests extends AbstractHttpHandlerIntegrationT
 
 	@ParameterizedHttpServerTest
 	void transferTo(HttpServer httpServer) throws Exception {
+		// TODO https://github.com/spring-projects/spring-framework/issues/35531
+		if (JRE.JAVA_25.isCurrentVersion()) {
+			assumeThat(httpServer).isNotInstanceOf(JettyHttpServer.class);
+		}
+
 		startServer(httpServer);
 
 		Flux<String> result = webClient