JDK 19 + Gradle 8.1.1 + kotlin 1.8.21 + spotless

buildSrc/src/main/kotlin/be/simplenotes/PostcssPlugin.kt

@@ -2,8 +2,10 @@ package be.simplenotes
 
 import org.gradle.api.Plugin
 import org.gradle.api.Project
-import org.gradle.api.plugins.JavaPluginConvention
+import org.gradle.api.plugins.JavaPluginExtension
+import org.gradle.api.tasks.SourceSetContainer
 import org.gradle.kotlin.dsl.get
+import org.gradle.kotlin.dsl.getByType
 import org.gradle.kotlin.dsl.register
 import java.io.File
 
@@ -17,7 +19,7 @@ class PostcssPlugin : Plugin<Project> {
             getByName("processResources").dependsOn("postcss")
         }
 
-        val sourceSets = project.convention.getPlugin(JavaPluginConvention::class.java).sourceSets
+        val sourceSets = project.extensions.getByType<SourceSetContainer>()
         val root = File("${project.buildDir}/generated-resources/css")
         sourceSets["main"].resources.srcDir(root)
     }

buildSrc/src/main/kotlin/be/simplenotes/java-convention.gradle.kts

@@ -12,8 +12,10 @@ group = "be.simplenotes"
 version = "1.0-SNAPSHOT"
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_15
-    targetCompatibility = JavaVersion.VERSION_15
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(19))
+        vendor.set(JvmVendorSpec.ORACLE)
+    }
 }
 
 tasks.withType<JavaCompile> {

buildSrc/src/main/kotlin/be/simplenotes/kotlin-convention.gradle.kts

@@ -1,5 +1,7 @@
 package be.simplenotes
 
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+import org.jetbrains.kotlin.gradle.dsl.KotlinVersion
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 plugins {
@@ -13,14 +15,14 @@ dependencies {
 }
 
 tasks.withType<KotlinCompile> {
-    kotlinOptions {
-        jvmTarget = "15"
-        javaParameters = true
-        freeCompilerArgs = listOf(
+    compilerOptions {
+        jvmTarget.set(JvmTarget.JVM_19)
+        javaParameters.set(true)
+        freeCompilerArgs.addAll(
             "-Xinline-classes",
             "-Xno-param-assertions",
             "-Xno-call-assertions",
-            "-Xno-receiver-assertions"
+            "-Xno-receiver-assertions",
         )
     }
 }