Use javac -release and kotlinc -Xjdk-release (#1080)

The change ensures the generated bytecode adheres to the APIs
for the target Java release.

Previously, only sourceCompatibility and targetCompatibility were used,
and they might cause issues like NoSuchMethodError when a newer javac
compiles with -target older_release.

Note: it is good to use a new an up to date javac to avoid issues
in the compiler itself, so having a proper `-release ..` configuration
is vital.

See https://www.morling.dev/blog/bytebuffer-and-the-dreaded-nosuchmethoderr

buildSrc/build.gradle.kts

@@ -35,16 +35,18 @@ dependencies {
 }
 
 java {
-  sourceCompatibility = JavaVersion.toVersion(toolchainVersion)
-  targetCompatibility = JavaVersion.toVersion(toolchainVersion)
-
   toolchain {
     languageVersion = JavaLanguageVersion.of(toolchainVersion)
     vendor = JvmVendorSpec.ADOPTIUM
   }
 }
 
+tasks.withType<JavaCompile>().configureEach { options.release = toolchainVersion }
+
 kotlin {
   jvmToolchain(toolchainVersion)
-  compilerOptions { jvmTarget = JvmTarget.fromTarget(toolchainVersion.toString()) }
+  compilerOptions {
+    jvmTarget = JvmTarget.fromTarget(toolchainVersion.toString())
+    freeCompilerArgs.add("-Xjdk-release=$toolchainVersion")
+  }
 }