build(gradle): Use Java 21 to build the workbench

This is a preparation for upgrading to ORT 35.0.0 which was built with
Java 21.

Even though GitHub runner image Ubuntu 24.04 still has Java 17 as the
default [1], it also has Java 21 installed and Gradle's toolchain
mechanism will find it without setting it up via the action.

[1]: https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2404-Readme.md#java

Signed-off-by: Sebastian Schuberth <[email protected]>

.github/workflows/build.yml

@@ -16,11 +16,6 @@ jobs:
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v4
-      - name: Setup Java
-        uses: actions/setup-java@v4
-        with:
-          distribution: temurin
-          java-version: 17
       - name: Build the JAR
         uses: gradle/gradle-build-action@v3
         with:

.github/workflows/static-analysis.yml

@@ -25,11 +25,6 @@ jobs:
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v4
-      - name: Setup Java
-        uses: actions/setup-java@v4
-        with:
-          distribution: temurin
-          java-version: 17
       - name: Run Detekt
         uses: gradle/gradle-build-action@v3
         with:

build.gradle.kts

@@ -7,6 +7,8 @@ import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 import org.jetbrains.kotlin.gradle.dsl.KotlinVersion
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
+val javaLanguageVersion: String by project
+
 plugins {
     alias(libs.plugins.compose)
     alias(libs.plugins.compose.compiler)
@@ -77,10 +79,15 @@ tasks.named<DependencyUpdatesTask>("dependencyUpdates") {
 }
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_17
-    targetCompatibility = JavaVersion.VERSION_17
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(javaLanguageVersion)
+        vendor = JvmVendorSpec.ADOPTIUM
+    }
 }
 
+val maxKotlinJvmTarget = runCatching { JvmTarget.fromTarget(javaLanguageVersion) }
+    .getOrDefault(enumValues<JvmTarget>().max())
+
 tasks.withType<KotlinCompile> {
     val customCompilerArgs = listOf(
         "-opt-in=androidx.compose.ui.ExperimentalComposeUiApi"
@@ -90,7 +97,7 @@ tasks.withType<KotlinCompile> {
         allWarningsAsErrors = true
         apiVersion = KotlinVersion.KOTLIN_1_8
         freeCompilerArgs.addAll(customCompilerArgs)
-        jvmTarget = JvmTarget.JVM_17
+        jvmTarget = maxKotlinJvmTarget
     }
 }
 
@@ -102,6 +109,8 @@ detekt {
 }
 
 tasks.withType<Detekt>().configureEach {
+    jvmTarget = maxKotlinJvmTarget.target
+
     reports {
         xml.required.set(false)
         html.required.set(false)

gradle.properties

@@ -3,4 +3,6 @@ org.gradle.configuration-cache = true
 org.gradle.kotlin.dsl.allWarningsAsErrors = true
 org.gradle.parallel = true
 
+javaLanguageVersion = 21
+
 kotlin.code.style = official